题解 | 二叉树的最小深度

import java.util.*;


/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 * }
 */

public class Solution {
    /**
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    public int run (TreeNode root) {
        if (root == null) {
            return 0;
        }
        if (root.left == null && root.right == null) {
            return 1;
        }
        if (root.left == null || root.right == null) {
            return Math.max(run(root.left), run(root.right)) + 1;
        }
        return Math.min(run(root.left), run(root.right)) + 1;
    }

}