leetCode - Minimum Depth of Binary Tree

题目描述
Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

就是求二叉树的最小深度。

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int run(TreeNode root) {
        if(root == null) {
            return 0;
        }
        else if(root.left == null && root.right == null) {
            return 1;
        } else if(root.left == null) {
            return run(root.right) + 1;
        } else if(root.right == null) {
            return run(root.left) + 1;
        } else {
            int left = run(root.left);
            int right = run(root.right);
            return left > right ? right + 1 : left + 1;
        }
    }
}