111. Minimum Depth of Binary Tree

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int minDepth(TreeNode root) {
        if(root==null)
            return 0;
        Queue<TreeNode> q=new LinkedList<TreeNode>();
        q.offer(root);
        int size=q.size();
        int res=1;
        int count=0;
        while(!q.isEmpty())
        {
            TreeNode temp=q.poll();
            if(temp.left==null&&temp.right==null)
            {
                //找到了叶子节点
                break;
            }
            if(temp.left!=null)
                q.offer(temp.left);
            if(temp.right!=null)
                q.offer(temp.right);
            count++;
            if(count==size)
            {
                count=0;
                size=q.size();
                res++;
            }
            
            
        }
        return res;
    }
}