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 TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    public int run (TreeNode root) {
        // write code here
        
        // 一些特殊情况的处理
        if (null == root) {
            return 0;
        }
        if (null == root.left && null == root.right) {
            return 1;
        }
        
        // 具体代码实现
        return process(root, 1);
    }
    
    public int process(TreeNode node, int level) {
        if (null == node.left && null == node.right) {
            return level;
        }
        level++;
        int ll = Integer.MAX_VALUE;
        int rl = Integer.MAX_VALUE;
        if (null != node.left) {
            ll = process(node.left, level);
        }
        if (null != node.right) {
            rl = process(node.right, level);
        }
        return Math.min(ll, rl);
    }
}