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.

題意很簡單，就是DFS深度優先遍歷。

程式碼如下：

/* class TreeNode 
 {
      int val;
      TreeNode left;
      TreeNode right;
      TreeNode(int x) { val = x; }
}*/
 


public class Solution 
{
    public boolean isSameTree(TreeNode p, TreeNode q) 
    {
        return isEqual(p,q);
    }
    //遞迴遍歷二叉樹
    private boolean isEqual(TreeNode p, TreeNode q) 
    {
        if(p==null && q==null)
            return true;
        else if(p==null && q!=null
 
 || p!=null && q==null )
            return false;
        else if(p.val==q.val)
            return isEqual(p.left, q.left) && isEqual(p.right, q.right);
        else 
            return false;
    }
}

下面是C++的做法，就是做一個DFS深度優先遍歷的做法，很簡單的

程式碼如下：

#include<iostream>
#include <vector>

using namespace std;


/*
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 || p != NULL && q == NULL)
            return false;
        else if (p == NULL && q == NULL)
            return true;
        else if (p->val != q->val)
            return false;
        else 
            return isSameTree(p->left,q->left) && isSameTree(p->right,q->right);

    }
};