Leetcode dfs Path SumII，leetcodesumii

Leetcode dfs Path SumII，leetcodesumii
Path Sum II Total Accepted: 18489 Total Submissions: 68323My Submissions

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]]

題意：給定一棵二叉樹和一個值，在二叉樹中找到從根到葉子的路徑使得路徑中的節點的總值
等於給定值
思路：dfs
複雜度：時間O(n) 空間O(log n)

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