leetcode - Path Sum II

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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]]

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */struct TreeNode{int val;TreeNode *left;TreeNode *right;TreeNode(int x) : val(x), left(NULL), right(NULL) {}};class Solution {public:std::vector<std::vector<int> > pathSum(TreeNode *root, int sum) {        dfs(root,sum,0,std::vector<int>(0));return res;    }private:std::vector<std::vector<int>> res;void dfs(TreeNode *root, int sum, int n,std::vector<int> vec){if(root == NULL) return;if(root->left == NULL && root->right == NULL){if(sum == root->val + n){vec.push_back(root->val);res.push_back(vec);}}else{vec.push_back(root->val);dfs(root->left,sum,n+root->val,vec);dfs(root->right,sum,n+root->val,vec);}}};

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