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]
]

 

 

Code:

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