题解 | #二叉树的最小深度#

BFS

import java.util.*;
public class Solution {
    public int run (TreeNode root) {
        if(root == null){
            return 0;
        }
        Queue q = new LinkedList();
        q.add(root);
        int depth = 1;
        while(!q.isEmpty()){
            int size = q.size();
            for(int i = 0;i<size;i++){
                TreeNode cur = q.poll();
                if(cur.left == null && cur.right == null){
                    return depth;
                }
                if(cur.left != null){
                    q.add(cur.left);
                }
                if(cur.right != null){
                    q.add(cur.right);
                }
            }
            depth++;
        }
        return depth;

    }
}