力扣hot100 91-100记录

91-100
（动态规划）

class Solution {
public:int uniquePaths(int m, int n) {vector<vector<int>> f(m, vector<int>(n, 1));for(int  i = 1; i < m; i++){for(int j = 1; j < n; j++){f[i][j] = f[i-1][j] + f[i][j-1];} }return f[m-1][n-1];        }
};//91

class Solution {
public:int minPathSum(vector<vector<int>>& grid) {int m = grid.size();if(m == 0) return 0;int n = grid[0].size();const int dr[2] = {1, 0};const int dd[2] = {0, 1};vector<vector<int>> f(m, vector<int>(n, INT_MAX));f[0][0] = grid[0][0];for(int i = 0; i < m; i++){for(int j = 0; j < n; j++){for(int d = 0; d < 2; d++){int ii = i + dr[d];int jj = j + dd[d];if(ii == m || jj == n) continue;f[ii][jj] = min(f[ii][jj], f[i][j] + grid[ii][jj]);}}}return f[m-1][n-1];}
};//92

class Solution {
public:pair<int, int> expandAroundCenter(const string& s, int left, int right) {while (left >= 0 && right < s.size() && s[left] == s[right]) {--left;++right;}return {left + 1, right - 1};}string longestPalindrome(string s) {int start = 0, end = 0;for (int i = 0; i < s.size(); ++i) {auto [left1, right1] = expandAroundCenter(s, i, i);auto [left2, right2] = expandAroundCenter(s, i, i + 1);if (right1 - left1 > end - start) {start = left1;end = right1;}if (right2 - left2 > end - start) {start = left2;end = right2;}}return s.substr(start, end - start + 1);}string longestPalindrome2(string s) {int n = s.size();if(n < 2) return s;int maxLen = 1;int begin = 0;vector<vector<int>> dp(n, vector<int>(n));for(int i =0; i<n; i++){dp[i][i] = true;}for(int L = 2; L <= n; L++){for(int i = 0; i < n; i++){int j = i + L - 1;if(j >= n) break;if(s[i] == s[j]){if(j - i < 3){dp[i][j] = true;}else{dp[i][j] = dp[i+1][j-1];}}else{dp[i][j] = false;}if(dp[i][j] && L > maxLen){maxLen = L;begin = i;}}}return s.substr(begin, maxLen);}
};//93

class Solution {
public:int longestCommonSubsequence(string text1, string text2) {int m = text1.size(), n = text2.size();vector<vector<int>> dp(m+1, vector<int>(n+1));for(int i = 1; i <= m; i++){char c1 = text1[i-1];for(int j = 1; j <= n; j++){char c2 = text2[j-1];if(c1 == c2){dp[i][j] = dp[i-1][j-1] + 1;}else{dp[i][j] = max(dp[i-1][j], dp[i][j-1]);}}}return dp[m][n];}
};//94

class Solution {
public:int minDistance(string word1, string word2) {int m = word1.size();int n = word2.size();if(n*m == 0) return n + m;vector<vector<int>> dp(m + 1, vector<int>(n + 1));for(int i = 0; i <= m; i++){dp[i][0] = i;}for(int j = 0; j <= n; j++){dp[0][j] = j;}for(int i = 1; i <= m; i++){for(int j = 1; j <= n; j++){int left = dp[i-1][j] + 1;int right = dp[i][j-1] + 1;int left_right = dp[i-1][j-1] + (word1[i-1] == word2[j-1] ? 0 : 1);dp[i][j] = min(left_right, min(left, right));}}return dp[m][n];}
};//95

class Solution {
public:int singleNumber(vector<int>& nums) {int ret = 0;for(auto num:nums){ret ^= num;}return ret;}
};//96

class Solution {
public:int majorityElement(vector<int>& nums) {unordered_map<int,int> counts;int duo=0, cnt=0;for(int num:nums){counts[num]++;if(counts[num] > cnt){cnt = counts[num];duo = num;}}return duo;}
};//97

class Solution {
public:void sortColors2(vector<int>& nums) {sort(nums.begin(),nums.end());}void sortColors(vector<int>& nums) {int n = nums.size();int ptr = 0;for(int i = 0; i < n; i++){if(nums[i] == 0){swap(nums[i], nums[ptr++]);}}for(int i = ptr; i < n; i++){if(nums[i] == 1){swap(nums[i], nums[ptr++]);}}}
};//98

class Solution {
public:void nextPermutation(vector<int>& nums) {next_permutation(nums.begin(), nums.end());}
};//99

class Solution {
public:int findDuplicate(vector<int>& nums) {int n = nums.size();int l = 1, r = n - 1, ans = -1;while(l <= r){int mid = (r + l) >> 1;int cnt = 0;for(int num : nums){cnt += num <= mid;}            if(cnt <= mid){l = mid + 1;}else{r = mid - 1;ans = mid;}}return ans;}
};//100