LeetCode Q129: Sum Root to Leaf Numbers

Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.

An example is the root-to-leaf path 1->2->3 which represents the number 123.

Find the total sum of all root-to-leaf numbers.

For example,

    1
   / \
  2   3

The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.

Return the sum = 12 + 13 = 25.

	/**
	* Definition for a binary tree node.
	* struct TreeNode {
	* int val;
	* TreeNode *left;
	* TreeNode *right;
	* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
	* };
	*/
	class Solution {
	public:
	void helper(TreeNode* root, int curSum, int& totalSum){
	if(root->left==NULL&&root->right==NULL){
	totalSum=totalSum+curSum*10+root->val;
	return;
	}
	curSum=curSum*10+root->val;
	if(root->left!=NULL)
	helper(root->left, curSum, totalSum);
	if(root->right!=NULL)
	helper(root->right, curSum, totalSum);
	}
	int sumNumbers(TreeNode* root) {
	if(root==NULL)
	return 0;
	int totalSum=0;
	helper(root, 0, totalSum);
	return totalSum;
	}
	};

view raw Q129.cpp hosted with ❤ by GitHub