leetcode_129题——Sum Root to Leaf Numbers（基于DFS的递归）

Sum Root to Leaf Numbers

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Question  Solution 

 

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.

 

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       这道题采用基于DFS的递归来做。

#include<iostream>

using namespace std;

struct TreeNode

{

	int val;

    TreeNode *left;

    TreeNode *right;

    TreeNode(int x) : val(x), left(NULL), right(NULL) {}

};

void digui(TreeNode* root,int len,int &result)

{

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

	{

		result=result+len;

		return;

	}

	if(root->left!=NULL)

	{

		digui(root->left,len*10+root->left->val,result);

	}

	if(root->right!=NULL)

	{

		digui(root->right,len*10+root->right->val,result);

	}

	return;

}

int sumNumbers(TreeNode* root){

	int last=0;

	if(root==NULL)

		return 0;

	digui(root,root->val,last);

	return last;

}

int main()

{

	TreeNode* root=new TreeNode(0);

	root->left=new TreeNode(1);

	root->right=new TreeNode(3);

	cout<<sumNumbers(root)<<endl;

}