【LeetCode题目记录-5】二叉树是否相同

Same Tree

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

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

【分析1-原创】递归判断

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if(p==null&&q==null){
            return true;
        }
        if((p==null&&q!=null)||(p!=null&&q==null)){
            return false;
        }
        return p.val==q.val?isSameTree(p.left, q.left)&&isSameTree(p.right, q.right):false;
    }
}

【分析2-非原创】参考：https://oj.leetcode.com/discuss/3470/seeking-for-better-solution

这里将前面的两条判断归为一条语句。

public boolean isSameTree(TreeNode p, TreeNode q) {
        if(p==null || q==null) {
            return p==q;
        } else
            return (p.val == q.val)&&isSameTree(p.left,q.left)&&isSameTree(p.right,q.right);
    }