回溯第二天

39. 组合总和

class Solution {
public:vector<vector<int>> result;vector<int> temp;void backTracking(int startIndex, int& Sum, vector<int>& candidates, int target){if(Sum > target) return;if(Sum == target){result.push_back(temp);return;} for(int i = startIndex; i < candidates.size(); i++){Sum += candidates[i];temp.push_back(candidates[i]);  backTracking(i, Sum, candidates, target);temp.pop_back();Sum -= candidates[i];}}vector<vector<int>> combinationSum(vector<int>& candidates, int target) {int Sum = 0;backTracking(0, Sum, candidates, target);return result;}
};

40. 组合总和 II

class Solution {
public:vector<vector<int>> result;vector<int> temp;void backTracking(int startIndex, int& Sum, vector<int>& candidates, int target, vector<bool>& used){if(Sum > target) return;if(Sum == target){result.push_back(temp);return;}for(int i = startIndex; i < candidates.size(); i++){if(i > 0 && candidates[i] == candidates[i - 1] && used[i - 1] == false)continue;used[i] = true;Sum += candidates[i];temp.push_back(candidates[i]);  backTracking(i + 1, Sum, candidates, target, used);temp.pop_back();Sum -= candidates[i];used[i] = false;}}vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {int Sum = 0;vector<bool> used(candidates.size(), false);sort(candidates.begin(), candidates.end());backTracking(0, Sum, candidates, target, used);return result;}
};

131. 分割回文串

class Solution {
public:vector<string> path;vector<vector<string>> result;bool isPalindrome(string s, int start, int end){for(int i = start, j = end; i <= j; i++, j--){if(s[i] != s[j])return false;}return true;}void backTracking(string s, int startIndex){if(startIndex >= s.size()){result.push_back(path);return;}for(int i = startIndex; i < s.size(); i++){if(isPalindrome(s, startIndex, i)){path.push_back(s.substr( startIndex, i - startIndex + 1));}elsecontinue;backTracking(s, i + 1 );path.pop_back();}}vector<vector<string>> partition(string s) {backTracking(s, 0);return result;}
};