[LeetCode] 113. Path Sum II

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.
Note: A leaf is a node with no children.
Example:

Given the below binary tree and sum = 22,

Return:
[
[5,4,11,2],
[5,8,4,5]
]

解析

返回所有路径等于sum的路径值，用vector存储。采用DFS。

代码

class Solution {
public:
    vector<vector<int>> pathSum(TreeNode* root, int sum) {
        vector<vector<int> > res;
        vector<int> path;
        findpath(root, sum, path, res);
        return res;
    }

    void findpath(TreeNode* root, int sum, vector<int> &path, vector<vector<int> > &res){
        if(!root) return;
        path.push_back(root->val);
        sum -= root->val;
        if(!root->left && !root->right && sum == 0)
            res.push_back(path);
        findpath(root->left, sum, path, res);
        findpath(root->right, sum, path, res);
        path.pop_back();
    }
};

参考

http://www.cnblogs.com/grandyang/p/4042156.html