111.二叉树的最小深度.cpp

/*
 * @lc app=leetcode.cn id=111 lang=cpp
 *
 * [111] 二叉树的最小深度
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int minDepth(TreeNode* root) {
        if(!root) return 0;
        queue<TreeNode*> q;
        q.push(root);

        int depth = 0;
        while(!q.empty())
        {
            int size = q.size();
            for(int i = 0; i < size; ++i)
            {
                TreeNode* curr = q.front();
                q.pop();
                if(curr->left) q.push(curr->left);
                if(curr->right) q.push(curr->right);
                if(!curr->left && !curr->right)
                {
                    return depth + 1;
                }
            }
            depth++;
        }
        return depth;
    }
};
// @lc code=end