leetcode-100-Same-Tree

描述


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


递归遍历二叉树,判断两棵树是否一样,注意边界情况。

解决方案1(C++)


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/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
bool isSameTree(TreeNode* p, TreeNode* q) {
if(p==NULL && q==NULL){
return true;
}
if(p==NULL&&q!=NULL || p!=NULL&&q==NULL){
return false;
}
if(p->val != q->val){
return false;
}
return (isSameTree(p->left, q->left) && isSameTree(p->right, q->right));
}
};

解决方案2(Python)

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# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def isSameTree(self, p, q):
"""
:type p: TreeNode
:type q: TreeNode
:rtype: bool
"""
if not p and not q:
return True
try:
if p.val == q.val and self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right):
return True
except AttributeError:
return False
return False

解决方案3(Java)

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/**
* 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 false;
}
return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}
}

题目来源