[leetcode] 113. Path Sum II 解题报告

题目链接：https://leetcode.com/problems/path-sum-ii/

Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5             / \            4   8           /   / \          11  13  4         /  \    / \        7    2  5   1

return

[   [5,4,11,2],   [5,8,4,5]]

思路：一个深度搜索，到叶子节点的时候看和是否等于给定的值即可。

代码如下：

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    void DFS(TreeNode* root, int sum, vector<int> path, int cur)    {        if(!root) return;        path.push_back(root->val);        if(!root->left && !root->right && cur+root->val==sum) result.push_back(path);        if(!root->left && !root->right) return;        DFS(root->left, sum, path, cur+root->val);        DFS(root->right, sum, path, cur+root->val);    }        vector<vector<int>> pathSum(TreeNode* root, int sum) {        if(!root) return result;        DFS(root, sum, vector<int>(),0);        return result;    }private:    vector<vector<int>> result;};