leetcode Sum Root to Leaf Numbers

最新推荐文章于 2025-12-27 15:35:24 发布

转载最新推荐文章于 2025-12-27 15:35:24 发布 · 116 阅读

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原文链接：http://www.cnblogs.com/GadyPu/p/5034066.html

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#数据结构与算法

本文详细解析了LeetCode上的一道经典题目——路径之和，通过递归深度优先搜索(DFS)的方法，计算二叉树中所有从根节点到叶子节点的路径所代表的数字之和。以示例说明，对于二叉树1->2和1->3，分别代表数字12和13，返回这两个数的总和25。

题目连接

https://leetcode.com/problems/sum-root-to-leaf-numbers/

Sum Root to Leaf Numbers

Description

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:
	int ans;
	int sumNumbers(TreeNode* root) {
		if (!root) return 0;
		ans = 0;
		dfs(root, 0);
		return ans;
	}
	void dfs(TreeNode *x, int v) {
		if (!x) return;
		if (!x->left && !x->right) {
			ans += x->val + v * 10;
		}
		dfs(x->left, v * 10 + x->val);
		dfs(x->right, v * 10 + x->val);
	}
};

转载于:https://www.cnblogs.com/GadyPu/p/5034066.html