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[LeetCode] 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]]

思路:与http://www.cnblogs.com/vincently/p/4130398.html一样的思路,只不过注意保存路径。
  时间复杂度O(n),空间复杂度O(lgN)
相关题目:《剑指offer》面试题25

 1 /** 2  * Definition for binary tree 3  * struct TreeNode { 4  *     int val; 5  *     TreeNode *left; 6  *     TreeNode *right; 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8  * }; 9  */10 class Solution {11 public:12     vector<vector<int> > pathSum(TreeNode *root, int sum) {13         vector<vector<int> > result;14         if (root == NULL) 15             return result;16             17         vector<int> path;18         pathSum(root, sum, result, path);19         20         return result;21     }22     23     void pathSum(TreeNode *root, int sum, vector<vector<int> > &result, vector<int> &path) {24         path.push_back(root->val);25         26         if (root->left == NULL && root->right == NULL) {27             if (root->val == sum) {28                 result.push_back(path);29             } 30         } 31         32         if (root->left) 33             pathSum(root->left, sum - root->val, result, path);34             35         if (root->right)36             pathSum(root->right, sum - root->val, result, path);37         38         path.pop_back();39             40     }41 };

 

[LeetCode] Path Sum II