算法作業HW28：LeetCode 100. Same Tree

Description:

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.

Note:

無

Solution:

  Analysis and Thinking:

題目要求在給定兩棵樹的情況下，判斷這兩棵樹是否相等，可以使用遞歸的方式實現

  Steps:

1. 判斷當前兩節點是否有任一爲空，如果有，表示不相等，返回false

2. 如果當前兩節點都爲空，表示兩棵樹都已經遍歷完畢，所有節點都相等，返回true

3. 如果兩節點都非空，比較節點的值，如果不等，返回false

4. 遞歸對兩節點的左子樹以及右子樹調用1~3步

Codes:

class Solution {
public:
    bool isSameTree(TreeNode *p, TreeNode *q) {
        if(p && !q)
            return false;
        else if(!p && q)
            return false;
        else if(!p && !q)
            return true;
        else
        {
            if(p->val != q->val)
                return false;
            else
                return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
        }
    }
};

Results: