Description:

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]]

Code:

1 void pathSum(TreeNode* root, int sum, vector
     
      &path,vector< vector
      
        >&result) 2     { 3         path.push_back(root->val); 4           if (root->left == NULL && root->right == NULL && root->val == sum) 5                     result.push_back(path); 6             if (root->left!=NULL) 7                 pathSum(root->left, sum-root->val, path,result); 8             if (root->right!=NULL) 9                 pathSum(root->right, sum-root->val, path,result);10             path.pop_back();   11     }12     vector
       
        
         > pathSum(TreeNode* root, int sum) {13         vector< vector
         
           >result;14         if (root==NULL)15            return result;   16         vector
          
           path;17 pathSum(root,sum,path,result);18 return result;19 }