【leetcode】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.

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]

]

 

 

采用深度优先搜索即可

 

 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<int> tmp;

14         vector<vector<int> > result;

15         if(root==NULL)

16         {

17             return result;

18         }

19         DFS(root,sum,tmp,result);

20         return result;

21        

22     }

23    

24     void DFS(TreeNode *root,int &sum, vector<int> tmp,vector<vector<int> > &result,int cur=0)

25     {

26         if(root==NULL)

27         {

28             return;

29         }

30  

31         int val=root->val;

32         tmp.push_back(val);

33        

34         if(root->left==NULL&&root->right==NULL)

35         {

36             if(cur+val==sum) result.push_back(tmp);

37             return;

38         }

39         DFS(root->left,sum,tmp,result,cur+val);

40         DFS(root->right,sum,tmp,result,cur+val);

41     }

42 };