113. 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]]

LeetCode AC代码：

/** * 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>> result;        vector<int> cur;        pathSum(root, sum, cur, result);        return result;    }    void pathSum(TreeNode *root, int sum, vector<int> &cur,                vector<vector<int>> &result) {        if (root == NULL) return;        cur.push_back(root->val);        if (root->left == NULL && root->right == NULL) {            if (root->val == sum)                result.push_back(cur);        }        pathSum(root->left, sum - root->val, cur, result);        pathSum(root->right, sum - root->val, cur, result);        cur.pop_back();    }};