leetcode Sum Root to Leaf Numbers 树

最新推荐文章于 2023-10-10 09:42:58 发布

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本文介绍了一种算法，用于计算二叉树中所有从根节点到叶子节点的路径所代表数字的总和。通过深度优先搜索遍历二叉树，并将路径上的数字转换为整数来实现。

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 dfs(TreeNode* root, int &sum, string str)
	{
		if (root==NULL)
		{
			return;
		}
		str.push_back(root->val+'0');
		if (root->left == NULL&&root->right == NULL)
		{
			sum += atoi(str.c_str());
			return;
		}
		dfs(root->left, sum, str);
		dfs(root->right, sum, str);
	}
	int sumNumbers(TreeNode* root) {
		if (root == NULL) return 0;
		int sum = 0;
		string str;
		dfs(root, sum, str);
		return sum;
	}
};