Same Tree

Description

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

Tags: Tree, Depth-first Search

思路

题意是比较两棵二叉树是否相同，那么我们就深搜比较各个节点即可。

java:

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

kotlin(184ms/100.00%):

class Solution {
    fun isSameTree(p: TreeNode?, q: TreeNode?): Boolean {
        if (p == null && q == null) return true
        if (p == null || q == null) return false
        return p.`val` == q.`val` && isSameTree(p.left, q.left) && isSameTree(p.right, q.right)
    }
}

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} p
 * @param {TreeNode} q
 * @return {boolean}
 */
var isSameTree = function(p, q) {
    if(p == null && q == null) return true
    if(p == null || q == null) return false
    if(p.val == q.val) {
        return isSameTree(p.left, q.left) && isSameTree(p.right, q.right)
    }
    return false
};

结语

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