[LeetCode] Minimum Depth of Binary Tree

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

二叉树的最小深度。

使用递归求解：

如果根节点为空，返回0。

如果左节点为空，递归计算右节点。

如果右节点为空，递归计算左节点。

返回1 + 左子树和右子树的最小深度。

/*** 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 minDepth(TreeNode* root) {if (root == nullptr)return 0;if (root->left == nullptr)return 1 + minDepth(root->right);if (root->right == nullptr)return 1 + minDepth(root->left);return 1 + min(minDepth(root->left), minDepth(root->right));}
};
// 6 ms