100. Same Tree

最新推荐文章于 2024-10-14 18:27:49 发布

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本文介绍了一种检查两棵二叉树是否完全相同的算法，并通过一个特殊的异常处理机制来优化递归过程，确保结构和节点值完全一致。

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Given two binary trees, write a function to check if they are the same or not.

Two binary trees are considered the same if they are structurally identical and the nodes have the same value.

Example 1:

Input:     1         1
          / \       / \
         2   3     2   3


        [1,2,3],   [1,2,3]

Output: true

Example 2:

Input:     1         1
          /           \
         2             2

        [1,2],     [1,null,2]

Output: false

Example 3:

Input:     1         1
          / \       / \
         2   1     1   2

        [1,2,1],   [1,1,2]

Output: false

算法本身很简单，提及的原因主要是学习了如何使用捕获异常Exception来中断递归操作。详细见Java 跳出递归循环问题解决办法

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    class StopRecursionException extends RuntimeException{
    }

    boolean isSame;

    public boolean isSameTree(TreeNode p, TreeNode q) {
        isSame = true;
        try{
            same(p, q);
        }catch(StopRecursionException e){
            return isSame;
        }
        return isSame;
    }
    public void same(TreeNode p, TreeNode q){
        if(p == null && q == null)
            return;
        else if(p == null || q == null || p.val != q.val){
            isSame = false;
            throw new StopRecursionException();
            //return;
        }
        same(p.left, q.left);
        same(p.right, q.right);
    }
}