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Leetcode 100 Same Tree

发表于 更新于 分类于 Valine：
本文字数： 1k 阅读时长 ≈ 1 分钟

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:

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

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

Output: true

Example 2:

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Input:     1         1
          /           \
         2             2

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

Output: false

Example 3:

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

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

Output: false

递归

递归的判断即可.

两个树相同 => 根节点相同并且左右子树都相同

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