[LeetCode]Path Sum II

题目解析:(链接)

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]
]

解题思路:

需要遍历所有路径

 1 /**
 2  * Definition for a binary tree node.
 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         vector<int> one_result;// 中间结果
15         pathSum(root, result, sum, one_result);
16         return result;
17     }
18 private:
19     void pathSum(TreeNode *root, vector<vector<int>> &result, int sum, vector<int> &one_result) {
20         if (root == nullptr) return;
21         
22         one_result.push_back(root->val);
23         if (root->left == nullptr && root->right == nullptr && sum == root->val) {//叶节点
24             result.push_back(one_result);
25         }
26         pathSum(root->left, result, sum - root->val, one_result);
27         pathSum(root->right, result, sum - root->val, one_result);
28         
29         one_result.pop_back();
30     }
31 };

 

posted @ 2015-12-19 14:41  skycore  阅读(134)  评论(0)  编辑  收藏  举报