leetcode No113. Path Sum II

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Question：

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]]

求路径和等于sum的路径

Algorithm：

DFS

Accepted Code：

/** * 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:    vector<vector<int>> pathSum(TreeNode* root, int sum) {        vector<vector<int>> res;        vector<int> temp;        help(root,res,temp,sum);        return res;    }    void help(TreeNode* root,vector<vector<int>> &res,vector<int> v,int sum)    {        if(root==NULL)            return;        v.push_back(root->val);        if(root->left==NULL&&root->right==NULL&&root->val==sum)        {            res.push_back(v);            return;        }        else if(root->left==NULL&&root->right==NULL)                return;        else        {            if(root->left)                help(root->left,res,v,sum-root->val);            if(root->right)                help(root->right,res,v,sum-root->val);        }    }};

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