[leetcode] Sum Root to Leaf Numbers

最新推荐文章于 2022-01-25 11:20:00 发布

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本文探讨了如何计算二叉树中从根节点到叶子节点的路径所组成的数字之和。通过DFS深度优先搜索算法，遍历每个路径并累加其数值，最终得到总和。

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.

class Solution {
public:
    int sumNumbers(TreeNode *root) {
		// Start typing your C/C++ solution below
		// DO NOT write int main() function
		if(!root)return 0;
		int itermedia=0,sum=0;
		DFS(root,itermedia,sum);
		return sum;
	}
	void DFS(TreeNode *root, int& itermedia, int& sum){
		itermedia=itermedia*10+root->val;
		if(!root->left && !root->right){
			sum+=itermedia;
			itermedia/=10;
			return;
		}
		if(root->left)
			DFS(root->left,itermedia,sum);
		if(root->right)
			DFS(root->right,itermedia,sum);
		itermedia/=10;
	}
};