代码随想录算法训练营第二十七天|● 39. 组合总和● 40.组合总和II● 131.分割回文串-优快云博客

本文链接：https://blog.youkuaiyun.com/minodeer/article/details/137384501

本文介绍了三个编程问题的解决方案：使用递归和深度优先搜索的组合总和类（组合总和和组合总和II），以及寻找分割回文串的方法。这些算法涉及到了IT技术中的动态规划和字符串处理。

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39. 组合总和

class Solution {
public:vector<vector<int>>b;
vector<int>a;
void dfs(vector<int>& candidates, int target,int sum,int s){
    if(target<sum)
    return ;
    if(target==sum){
        b.push_back(a);
        return ;
    }
    for(int i=s;i<candidates.size();i++){
        a.push_back(candidates[i]);
        dfs(candidates,target,sum+candidates[i],i);
        a.pop_back();
    }
}
    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
        dfs(candidates,target,0,0);
        return b;
    }
};

40.组合总和II

class Solution {
public:
    vector<vector<int>> b;
    vector<int> a;
    void dfs(vector<int>& candidates, int target, int sum, int s,vector<bool>& mark) {
        if (sum > target)
            return;
        if (sum == target) {
            b.push_back(a);
            return;
        }
        for (int i = s ; i < candidates.size(); i++) {
           if(i > 0 && candidates[i] == candidates[i - 1] && !mark[i-1])
                continue;
            a.push_back(candidates[i]);
            mark[i] = 1;
            dfs(candidates, target, sum + candidates[i], i+1, mark);
            a.pop_back();
            mark[i] = 0;
        }
    }
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        vector<bool> mark(candidates.size(), 0);
        sort(candidates.begin(), candidates.end());
        dfs(candidates, target, 0, 0, mark);
        return b;
    }
};

131.分割回文串

class Solution {
public:
    vector<vector<string>> b;
    vector<string> a;
    bool huiwen(string s, int l, int r) {
        if (l == r)
            return 1;
        for (; l < r; l++, r--) {
            if (s[l] != s[r])
                return 0;
        }
        return 1;
    }
    void dfs(string s, int k) {
        if (k >= s.size()) {
            b.push_back(a);
            return;
        }
        for (int i = k; i < s.size(); i++) {
            string q(s.begin() + k, s.begin() + i+1);
            if (huiwen(s, k, i)) {
                cout<<q<<" ";
                a.push_back(q);
                dfs(s, i + 1);
                a.pop_back();
            }
        }
    }
    vector<vector<string>> partition(string s) {
        dfs(s, 0);
        return b;
    }
};