代码随想录Day23

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LeetCode39.组合总和

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

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LeetCode40.组合总和Ⅱ

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

LeetCode131.分割回文串

class Solution {
public:
    vector<string> path;
    vector<vector<string>> result;
    vector<vector<string>> partition(string s) {
        dfs(s);
        return result;
    }
    bool judge(std::string str){
        if(str == "")return false;
        int i = 0, j = static_cast<int>(str.length()) - 1;
        while(j > i){
            if(str[j] != str[i])return false;
            j--;
            i++;
        }
        return true;
    }
    void dfs(string s){
        if(judge(s)){
            path.push_back(s);
            result.push_back(path);
            path.pop_back();
        }
        for(int i = 0; i < s.length(); i++){
            string sub_str1, sub_str2;
            sub_str1 = s.substr(0, i + 1);
            sub_str2 = s.substr(i + 1, s.length() - i - 1);
            if(judge(sub_str1)){
                path.push_back(sub_str1);
                dfs(sub_str2);
                path.pop_back();
            }
        }
    }
};