113. Path Sum II

两次AC，第一次错误在于没有考虑可能会有负数结点的出现。

/** * 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:    void find(TreeNode* root, int sum,int target,vector<int>& temp,vector<vector<int>>& result)    {        if(sum==target&&root->left==NULL&&root->right==NULL)            result.push_back(temp);        else        {            if(root==NULL)                return;            else            {                if(root->left!=NULL)                {                    temp.push_back(root->left->val);                    find(root->left,sum+(root->left->val),target,temp,result);                    temp.pop_back();                }                if(root->right!=NULL)                {                    temp.push_back(root->right->val);                    find(root->right,sum+(root->right->val),target,temp,result);                    temp.pop_back();                }            }        }        return;    }    vector<vector<int>> pathSum(TreeNode* root, int sum) {        vector<vector<int>> result;        if(root==NULL)            return result;        else        {            vector<int> temp;            temp.push_back(root->val);            find(root,root->val,sum,temp,result);            return result;        }    }};