Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Commit 3d36b1e

Browse files
20200829
1 parent ffbe037 commit 3d36b1e

6 files changed

+186
-0
lines changed

‎Java/115.distinct-subsequences.java‎

Lines changed: 34 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
1+
/*
2+
* @lc app=leetcode id=115 lang=java
3+
*
4+
* [115] Distinct Subsequences
5+
*/
6+
7+
// @lc code=start
8+
class Solution {
9+
/*
10+
DP dp[i][j] : t的(1,i)部分和s的(1,j)部分相等的subsequences数
11+
padding : dp[0][*] = 1 t为"",s中有一个subsequence""和之匹配
12+
if t[i] = s[j] dp[i][j] = dp[i- 1][j - 1] # t[i]和s[j]在subsequence中匹配
13+
+ dp[i][j - 1] # s[j]不在subsequence中,和s(0, j-1)结果相同
14+
else dp[i][j] = dp[i][j - 1] # s多加一个j不会改变subsequences数
15+
*/
16+
public int numDistinct(String s, String t) {
17+
// t.size() < s.size()
18+
int m = t.length(), n = s.length();
19+
int[][] dp = new int[m + 1][n + 1];
20+
Arrays.fill(dp[0], 1);
21+
for (int i = 1; i <= m; ++i) {
22+
for (int j = 1; j <= n; ++j) {
23+
if (t.charAt(i - 1) == s.charAt(j - 1)) {
24+
dp[i][j] = dp[i - 1][j - 1] + dp[i][j - 1];
25+
} else {
26+
dp[i][j] = dp[i][j - 1];
27+
}
28+
}
29+
}
30+
return dp[m][n];
31+
}
32+
}
33+
// @lc code=end
34+
Lines changed: 43 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,43 @@
1+
/*
2+
* @lc app=leetcode id=188 lang=java
3+
*
4+
* [188] Best Time to Buy and Sell Stock IV
5+
*/
6+
7+
// @lc code=start
8+
class Solution {
9+
/*
10+
如果k >= prices.length / 2, 则视为可以无限次交易
11+
我们定义local[i][j]为在到达第i天时最多可进行j次交易并且最后一次交易在最后一天卖出的最大利润,此为局部最优。然后我们定义global[i][j]为在到达第i天时最多可进行j次交易的最大利润,此为全局最优。它们的递推式为:
12+
local[i][j] = max(global[i - 1][j - 1] + max(diff, 0), local[i - 1][j] + diff)
13+
global[i][j] = max(local[i][j], global[i - 1][j])
14+
time: O(kn)
15+
space: O(k)
16+
*/
17+
public int maxProfit(int k, int[] prices) {
18+
if (prices == null || prices.length == 0) return 0;
19+
if (k >= prices.length / 2) return unlimitedProfit(prices);
20+
int[] local = new int[k + 1];
21+
int[] global = new int[k + 1];
22+
for (int i = 0; i < prices.length - 1; ++i) {
23+
int diff = prices[i + 1] - prices[i];
24+
for (int j = k; j >= 1; --j) {
25+
local[j] = Math.max(global[j - 1] + Math.max(diff, 0), local[j] + diff);
26+
global[j] = Math.max(global[j], local[j]);
27+
}
28+
}
29+
return global[k];
30+
}
31+
32+
private int unlimitedProfit(int[] prices) {
33+
int res = 0;
34+
for (int i = 0; i < prices.length - 1; ++i) {
35+
if (prices[i + 1] - prices[i] > 0) {
36+
res += prices[i + 1] - prices[i];
37+
}
38+
}
39+
return res;
40+
}
41+
}
42+
// @lc code=end
43+
Lines changed: 30 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,30 @@
1+
/*
2+
* @lc app=leetcode id=435 lang=java
3+
*
4+
* [435] Non-overlapping Intervals
5+
*/
6+
7+
// @lc code=start
8+
class Solution {
9+
/*
10+
因为是比较end,所以按照end排序
11+
找到排序之后最多有多少non overlapping
12+
time: O(nlogn)
13+
space: O(1)
14+
*/
15+
public int eraseOverlapIntervals(int[][] intervals) {
16+
if (intervals == null || intervals.length == 0) return 0;
17+
Arrays.sort(intervals, (a, b) -> (a[1] - b[1]));
18+
int count = 1;
19+
int end = intervals[0][1];
20+
for (int i = 1; i < intervals.length; ++i) {
21+
if (intervals[i][0] >= end) {
22+
end = intervals[i][1];
23+
count++;
24+
}
25+
}
26+
return intervals.length - count;
27+
}
28+
}
29+
// @lc code=end
30+
Lines changed: 34 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
1+
/*
2+
* @lc app=leetcode id=470 lang=java
3+
*
4+
* [470] Implement Rand10() Using Rand7()
5+
*/
6+
7+
// @lc code=start
8+
/**
9+
* The rand7() API is already defined in the parent class SolBase.
10+
* public int rand7();
11+
* @return a random integer in the range 1 to 7
12+
*/
13+
class Solution extends SolBase {
14+
/*
15+
rand7() will get random 1 ~ 7
16+
(rand7() - 1) * 7 + rand7() - 1 will get random 0 ~ 48
17+
We discard 40 ~ 48, now we have rand40 equals to random 0 ~ 39.
18+
We just need to return rand40 % 10 + 1 and we get random 1 ~ 10.
19+
20+
In 9/49 cases, we need to start over again.
21+
In 40/49 cases, we call rand7() two times.
22+
23+
Overall, we need 49/40*2 = 2.45 calls of rand7() per rand10().
24+
*/
25+
public int rand10() {
26+
int rand40 = 40;
27+
while (rand40 >= 40) {
28+
rand40 = (rand7() - 1) * 7 + (rand7() - 1);
29+
}
30+
return rand40 % 10 + 1;
31+
}
32+
}
33+
// @lc code=end
34+

‎Java/767.reorganize-string.java‎

Lines changed: 43 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,43 @@
1+
/*
2+
* @lc app=leetcode id=767 lang=java
3+
*
4+
* [767] Reorganize String
5+
*/
6+
7+
// @lc code=start
8+
class Solution {
9+
/*
10+
先放频率最高的字符,再按位置插入
11+
time: O(n)
12+
space: O(1)
13+
*/
14+
public String reorganizeString(String S) {
15+
int[] freq = new int[26];
16+
char maxChar = 'a';
17+
int maxFreq = 0;
18+
for (char c : S.toCharArray()) {
19+
freq[c - 'a']++;
20+
if (freq[c - 'a'] > maxFreq) {
21+
maxChar = c;
22+
maxFreq = freq[c - 'a'];
23+
}
24+
}
25+
if (maxFreq > (S.length() + 1) / 2) return ""; // "aba"
26+
char[] res = new char[S.length()];
27+
int i = 0;
28+
while (freq[maxChar - 'a']-- > 0) {
29+
res[i] = maxChar;
30+
i += 2;
31+
}
32+
for (char c = 'a'; c <= 'z'; ++c) {
33+
while (freq[c - 'a']-- > 0) {
34+
if (i >= S.length()) i = 1;
35+
res[i] = c;
36+
i += 2;
37+
}
38+
}
39+
return new String(res);
40+
}
41+
}
42+
// @lc code=end
43+

‎README.md‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -38,6 +38,7 @@
3838
[42. trapping rain water](https://leetcode.com/problems/trapping-rain-water/) | [DP优化为two pointer](https://github.com/Yukinichi/leetcode/blob/master/Java/42.trapping-rain-water.java)
3939
[72. Edit Distance](https://leetcode.com/problems/edit-distance/) | [Solution](https://github.com/Yukinichi/leetcode/blob/master/Java/72.edit-distance.java)
4040
[96. Unique Binary Search Trees](https://leetcode.com/problems/unique-binary-search-trees/) | [Solution](https://github.com/Yukinichi/leetcode/blob/master/Java/96.unique-binary-search-trees.java)
41+
[188. Best Time to Buy and Sell Stock IV](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv/) | [局部最优vs全局最优](https://github.com/Yukinichi/leetcode/blob/master/Java/188.best-time-to-buy-and-sell-stock-iv.java)
4142
[300. Longest Increasing Subsequence(LIS)](https://leetcode.com/problems/longest-increasing-subsequence/) | [DP + binary search(C++)](https://github.com/Yukinichi/leetcode/blob/master/Cpp/300.longest-increasing-subsequence.cpp)
4243
[368. Largest Divisible Subset](https://leetcode.com/problems/largest-divisible-subset/) | [LIS问题变种](https://github.com/Yukinichi/leetcode/blob/master/Java/368.largest-divisible-subset.java)
4344
[354. Russian Doll Envelopes](https://leetcode.com/problems/russian-doll-envelopes/)|[Binary Search+DP(思路同lc300)](https://github.com/Yukinichi/leetcode/blob/master/Java/354.russian-doll-envelopes.java)
@@ -122,6 +123,7 @@
122123
:- | :-:
123124
[528. Random Pick with Weight](https://leetcode.com/problems/random-pick-with-weight/) | [Random + binarySeach](https://github.com/Yukinichi/leetcode/blob/master/Java/528.random-pick-with-weight.java)
124125
[384. Shuffle an Array](https://leetcode.com/problems/shuffle-an-array/) | [inside-out shuffle](https://github.com/Yukinichi/leetcode/blob/master/Java/384.shuffle-an-array.java)
126+
[470. Implement Rand10() Using Rand7()](https://leetcode.com/problems/implement-rand10-using-rand7/) | [Solution](https://github.com/Yukinichi/leetcode/blob/master/Java/470.implement-rand-10-using-rand-7.java)
125127

126128
## Search
127129
| Problem | Solution

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /