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Commit 4d8e387

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feat: add solutions to lcp problems: No.77,78 (doocs#1218)
* No.77.符文储备 * No.78.城墙防线
1 parent 0a6a47a commit 4d8e387

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12 files changed

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12 files changed

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‎lcp/LCP 77. 符文储备/README.md‎

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@@ -38,22 +38,105 @@
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<!-- 这里可写通用的实现逻辑 -->
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**方法一:排序**
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我们可以将符文按照魔力值从小到大排序,然后使用双指针维护一个滑动窗口,使得滑动窗口中的任意相邻的两块符文之间的魔力值相差不超过,找出满足条件的最大窗口长度即可。
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时间复杂度 $O(n \times \log n),ドル空间复杂度 $O(\log n)$。其中 $n$ 是数组 $runes$ 的长度。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
48-
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class Solution:
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def runeReserve(self, runes: List[int]) -> int:
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runes.sort()
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ans = i = 0
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for j, x in enumerate(runes):
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if j and runes[j] - runes[j - 1] > 1:
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i = j
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else:
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ans = max(ans, j - i + 1)
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return ans
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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public int runeReserve(int[] runes) {
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Arrays.sort(runes);
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int ans = 0;
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for (int i = 0, j = 0; j < runes.length; ++j) {
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if (j > 0 && runes[j] - runes[j - 1] > 1) {
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i = j;
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} else {
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ans = Math.max(ans, j - i + 1);
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}
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}
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return ans;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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int runeReserve(vector<int>& runes) {
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sort(runes.begin(), runes.end());
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int ans = 0;
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for (int i = 0, j = 0; j < runes.size(); ++j) {
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if (j && runes[j] - runes[j - 1] > 1) {
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i = j;
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} else {
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ans = max(ans, j - i + 1);
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}
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}
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return ans;
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}
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};
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```
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### **Go**
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```go
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func runeReserve(runes []int) (ans int) {
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sort.Ints(runes)
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i := 0
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for j, x := range runes {
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if j > 0 && x-runes[j-1] > 1 {
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i = j
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} else if t := j - i + 1; ans < t {
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ans = t
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}
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}
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return
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}
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```
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### **TypeScript**
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```ts
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function runeReserve(runes: number[]): number {
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runes.sort((a, b) => a - b);
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let ans = 0;
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let i = 0;
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for (let j = 0; j < runes.length; ++j) {
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if (j > 0 && runes[j] - runes[j - 1] > 1) {
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i = j;
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} else {
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ans = Math.max(ans, j - i + 1);
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}
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}
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return ans;
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}
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```
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### **...**
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class Solution {
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public:
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int runeReserve(vector<int>& runes) {
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sort(runes.begin(), runes.end());
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int ans = 0;
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for (int i = 0, j = 0; j < runes.size(); ++j) {
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if (j && runes[j] - runes[j - 1] > 1) {
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i = j;
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} else {
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ans = max(ans, j - i + 1);
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}
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}
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return ans;
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}
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};

‎lcp/LCP 77. 符文储备/Solution.go‎

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func runeReserve(runes []int) (ans int) {
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sort.Ints(runes)
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i := 0
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for j, x := range runes {
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if j > 0 && x-runes[j-1] > 1 {
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i = j
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} else if t := j - i + 1; ans < t {
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ans = t
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}
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}
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return
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}
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class Solution {
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public int runeReserve(int[] runes) {
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Arrays.sort(runes);
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int ans = 0;
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for (int i = 0, j = 0; j < runes.length; ++j) {
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if (j > 0 && runes[j] - runes[j - 1] > 1) {
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i = j;
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} else {
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ans = Math.max(ans, j - i + 1);
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}
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}
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return ans;
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}
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}

‎lcp/LCP 77. 符文储备/Solution.py‎

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class Solution:
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def runeReserve(self, runes: List[int]) -> int:
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runes.sort()
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ans = i = 0
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for j, x in enumerate(runes):
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if j and runes[j] - runes[j - 1] > 1:
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i = j
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else:
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ans = max(ans, j - i + 1)
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return ans

‎lcp/LCP 77. 符文储备/Solution.ts‎

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function runeReserve(runes: number[]): number {
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runes.sort((a, b) => a - b);
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let ans = 0;
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let i = 0;
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for (let j = 0; j < runes.length; ++j) {
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if (j > 0 && runes[j] - runes[j - 1] > 1) {
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i = j;
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} else {
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ans = Math.max(ans, j - i + 1);
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}
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}
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return ans;
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}

‎lcp/LCP 78. 城墙防线/README.md‎

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Original file line numberDiff line numberDiff line change
@@ -46,22 +46,187 @@
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<!-- 这里可写通用的实现逻辑 -->
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**方法一:二分查找**
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我们注意到,如果一个膨胀值 $x$ 满足条件,那么所有小于 $x$ 的值也都满足条件,这存在着单调性。因此我们可以使用二分查找的方法,找到最大的满足条件的膨胀值。
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我们定义二分查找的左边界 $left=0,ドル $right=rampart[1][0]-rampart[0][1]+rampart[2][0]-rampart[1][1],ドル其中 $rampart[i][0]$ 表示第 $i$ 段城墙的左端点,$rampart[i][1]$ 表示第 $i$ 段城墙的右端点。
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接下来,我们开始进行二分查找。每一次,我们求出当前的中间值 $mid,ドル并判断其是否满足条件。如果满足条件,那么我们就将左边界 $left$ 更新为 $mid,ドル否则将右边界 $right$ 更新为 $mid-1$。在二分查找结束后,我们返回左边界 $left$ 即可。
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那么问题的关键在于如何判断一个值 $w$ 是否满足条件。显然,我们可以用贪心的策略,每次先尽可能往左膨胀,如果还有剩余的膨胀值,再往右膨胀,如果在向右膨胀的过程中,发生了重叠,那么说明当前的膨胀值 $w$ 不满足条件,直接返回 `false` 即可。否则,遍历结束,返回 `true`。
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时间复杂度 $O(n \times \log M),ドル其中 $n$ 和 $M$ 分别是数组 $rampart$ 的长度和二分查找的右边界,本题中右边界最大为 $range=rampart[1][0]-rampart[0][1]+rampart[2][0]-rampart[1][1]$。空间复杂度 $O(1)$。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def rampartDefensiveLine(self, rampart: List[List[int]]) -> int:
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def check(w: int) -> bool:
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last = rampart[0][1]
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for i in range(1, len(rampart) - 1):
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x, y = rampart[i]
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a = x - last
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b = max(w - a, 0)
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if y + b > rampart[i + 1][0]:
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return False
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last = y + b
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return True
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left, right = 0, rampart[1][0] - rampart[0][1] + rampart[2][0] - rampart[1][1]
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while left < right:
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mid = (left + right + 1) >> 1
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if check(mid):
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left = mid
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else:
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right = mid - 1
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return left
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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private int[][] rampart;
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public int rampartDefensiveLine(int[][] rampart) {
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this.rampart = rampart;
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int left = 0, right = rampart[1][0] - rampart[0][1] + rampart[2][0] - rampart[1][1];
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while (left < right) {
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int mid = (left + right + 1) >> 1;
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if (check(mid)) {
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left = mid;
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} else {
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right = mid - 1;
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}
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}
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return left;
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}
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private boolean check(int w) {
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int last = rampart[0][1];
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for (int i = 1; i < rampart.length - 1; ++i) {
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int x = rampart[i][0], y = rampart[i][1];
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int a = x - last;
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int b = Math.max(w - a, 0);
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if (y + b > rampart[i + 1][0]) {
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return false;
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}
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last = y + b;
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}
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return true;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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int rampartDefensiveLine(vector<vector<int>>& rampart) {
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int left = 0, right = rampart[1][0] - rampart[0][1] + rampart[2][0] - rampart[1][1];
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auto check = [&](int w) {
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int last = rampart[0][1];
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for (int i = 1; i < rampart.size() - 1; ++i) {
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int x = rampart[i][0], y = rampart[i][1];
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int a = x - last;
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int b = max(w - a, 0);
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if (y + b > rampart[i + 1][0]) {
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return false;
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}
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last = y + b;
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}
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return true;
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};
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while (left < right) {
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int mid = (left + right + 1) >> 1;
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if (check(mid)) {
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left = mid;
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} else {
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right = mid - 1;
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}
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}
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return left;
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}
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};
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```
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### **Go**
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```go
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func rampartDefensiveLine(rampart [][]int) int {
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check := func(w int) bool {
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last := rampart[0][1]
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for i := 1; i < len(rampart)-1; i++ {
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x, y := rampart[i][0], rampart[i][1]
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a := x - last
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b := max(w-a, 0)
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if y+b > rampart[i+1][0] {
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return false
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}
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last = y + b
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}
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return true
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}
180+
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left, right := 0, rampart[1][0]-rampart[0][1]+rampart[2][0]-rampart[1][1]
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for left < right {
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mid := (left + right + 1) >> 1
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if check(mid) {
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left = mid
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} else {
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right = mid - 1
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}
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}
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return left
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}
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func max(a, b int) int {
194+
if a > b {
195+
return a
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}
197+
return b
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}
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```
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### **TypeScript**
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```ts
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function rampartDefensiveLine(rampart: number[][]): number {
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const check = (w: number): boolean => {
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let last = rampart[0][1];
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for (let i = 1; i < rampart.length - 1; ++i) {
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const [x, y] = rampart[i];
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const a = x - last;
210+
const b = Math.max(w - a, 0);
211+
if (y + b > rampart[i + 1][0]) {
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return false;
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}
214+
last = y + b;
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}
216+
return true;
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};
218+
let left = 0;
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let right = rampart[1][0] - rampart[0][1] + rampart[2][0] - rampart[1][1];
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while (left < right) {
221+
const mid = (left + right + 1) >> 1;
222+
if (check(mid)) {
223+
left = mid;
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} else {
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right = mid - 1;
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}
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}
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return left;
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}
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```
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### **...**
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class Solution {
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public:
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int rampartDefensiveLine(vector<vector<int>>& rampart) {
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int left = 0, right = rampart[1][0] - rampart[0][1] + rampart[2][0] - rampart[1][1];
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auto check = [&](int w) {
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int last = rampart[0][1];
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for (int i = 1; i < rampart.size() - 1; ++i) {
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int x = rampart[i][0], y = rampart[i][1];
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int a = x - last;
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int b = max(w - a, 0);
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if (y + b > rampart[i + 1][0]) {
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return false;
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}
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last = y + b;
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}
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return true;
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};
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while (left < right) {
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int mid = (left + right + 1) >> 1;
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if (check(mid)) {
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left = mid;
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} else {
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right = mid - 1;
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}
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}
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return left;
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}
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};

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