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Commit f493f41

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feat: add solutions to lcof2 problems: No.011,012
1 parent 50e10ca commit f493f41

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8 files changed

+190
-2
lines changed

8 files changed

+190
-2
lines changed

‎lcof2/剑指 Offer II 011. 0 和 1 个数相同的子数组/README.md‎

Lines changed: 57 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -40,22 +40,78 @@
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<!-- 这里可写通用的实现逻辑 -->
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前缀和加哈希表,把 0 当作 -1 处理,题目变成求和为 0 的子数组
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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
50-
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class Solution:
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def findMaxLength(self, nums: List[int]) -> int:
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m = {0: -1}
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ans, sum = 0, 0
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for i, num in enumerate(nums):
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sum += 1 if num == 1 else -1
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if sum in m:
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ans = max(ans, i - m[sum])
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else:
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m[sum] = i
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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 findMaxLength(int[] nums) {
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Map<Integer, Integer> m = new HashMap<>();
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m.put(0, -1);
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int ans = 0, sum = 0;
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for (int i = 0; i < nums.length; i++) {
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sum += nums[i] == 1 ? 1 : -1;
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if (m.containsKey(sum)) {
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ans = Math.max(ans, i - m.get(sum));
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} else {
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m.put(sum, i);
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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 findMaxLength(nums []int) int {
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m := map[int]int{0: -1}
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ans, sum := 0, 0
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for i, num := range nums {
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if num == 0 {
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sum -= 1
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} else {
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sum += 1
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}
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if j, ok := m[sum]; ok {
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ans = max(ans, i-j)
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} else {
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m[sum] = i
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}
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}
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return ans
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}
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func max(a, b int) int {
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if a > b {
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return a
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}
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return b
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}
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```
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### **...**
Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
func findMaxLength(nums []int) int {
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m := map[int]int{0: -1}
3+
ans, sum := 0, 0
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for i, num := range nums {
5+
if num == 0 {
6+
sum -= 1
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} else {
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sum += 1
9+
}
10+
if j, ok := m[sum]; ok {
11+
ans = max(ans, i-j)
12+
} else {
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m[sum] = i
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}
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}
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return ans
17+
}
18+
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func max(a, b int) int {
20+
if a > b {
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return a
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}
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return b
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}
Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,16 @@
1+
class Solution {
2+
public int findMaxLength(int[] nums) {
3+
Map<Integer, Integer> m = new HashMap<>();
4+
m.put(0, -1);
5+
int ans = 0, sum = 0;
6+
for (int i = 0; i < nums.length; i++) {
7+
sum += nums[i] == 1 ? 1 : -1;
8+
if (m.containsKey(sum)) {
9+
ans = Math.max(ans, i - m.get(sum));
10+
} else {
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m.put(sum, i);
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}
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}
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return ans;
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}
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}
Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,11 @@
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class Solution:
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def findMaxLength(self, nums: List[int]) -> int:
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m = {0: -1}
4+
ans, sum = 0, 0
5+
for i, num in enumerate(nums):
6+
sum += 1 if num == 1 else -1
7+
if sum in m:
8+
ans = max(ans, i - m[sum])
9+
else:
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m[sum] = i
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return ans

‎lcof2/剑指 Offer II 012. 左右两边子数组的和相等/README.md‎

Lines changed: 44 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -61,22 +61,65 @@
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<!-- 这里可写通用的实现逻辑 -->
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用前缀和进行预处理,避免重复计算
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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
71-
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class Solution:
74+
def pivotIndex(self, nums: List[int]) -> int:
75+
n = len(nums)
76+
sum = [0 for _ in range(n + 1)]
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for i in range(1, n + 1):
78+
sum[i] = sum[i - 1] + nums[i - 1]
79+
for i in range(0, n):
80+
if sum[i] == sum[n] - sum[i + 1]:
81+
return i
82+
return -1
7283
```
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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
90+
class Solution {
91+
public int pivotIndex(int[] nums) {
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int n = nums.length;
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int[] sum = new int[n + 1];
94+
for (int i = 1; i <= n; i++) {
95+
sum[i] = sum[i - 1] + nums[i - 1];
96+
}
97+
for (int i = 0; i < n; i++) {
98+
if (sum[i] == sum[n] - sum[i + 1]) {
99+
return i;
100+
}
101+
}
102+
return -1;
103+
}
104+
}
105+
```
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### **Go**
108+
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```go
110+
func pivotIndex(nums []int) int {
111+
n := len(nums)
112+
sum := make([]int, n+1)
113+
for i := 1; i <= n; i++ {
114+
sum[i] = sum[i-1] + nums[i-1]
115+
}
116+
for i := 0; i < n; i++ {
117+
if sum[i] == sum[n]-sum[i+1] {
118+
return i
119+
}
120+
}
121+
return -1
122+
}
80123
```
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82125
### **...**
Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,13 @@
1+
func pivotIndex(nums []int) int {
2+
n := len(nums)
3+
sum := make([]int, n+1)
4+
for i := 1; i <= n; i++ {
5+
sum[i] = sum[i-1] + nums[i-1]
6+
}
7+
for i := 0; i < n; i++ {
8+
if sum[i] == sum[n]-sum[i+1] {
9+
return i
10+
}
11+
}
12+
return -1
13+
}
Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
class Solution {
2+
public int pivotIndex(int[] nums) {
3+
int n = nums.length;
4+
int[] sum = new int[n + 1];
5+
for (int i = 1; i <= n; i++) {
6+
sum[i] = sum[i - 1] + nums[i - 1];
7+
}
8+
for (int i = 0; i < n; i++) {
9+
if (sum[i] == sum[n] - sum[i + 1]) {
10+
return i;
11+
}
12+
}
13+
return -1;
14+
}
15+
}
Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
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class Solution:
2+
def pivotIndex(self, nums: List[int]) -> int:
3+
n = len(nums)
4+
sum = [0 for _ in range(n + 1)]
5+
for i in range(1, n + 1):
6+
sum[i] = sum[i - 1] + nums[i - 1]
7+
for i in range(0, n):
8+
if sum[i] == sum[n] - sum[i + 1]:
9+
return i
10+
return -1

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