111. Minimum Depth of Binary Tree(Leetcode每日一题-2020.08.21)

Problem

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.

Note: A leaf is a node with no children.

Example

Solution

/**
 * 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)
            return 0;
        int leftMinDepth = minDepth(root->left);
        int rightMinDepth = minDepth(root->right);

        if(leftMinDepth && rightMinDepth)
            return min(leftMinDepth,rightMinDepth) + 1;
        else if(leftMinDepth == 0)
            return rightMinDepth + 1;
        else
            return leftMinDepth + 1;
        
    }
};