[Leetcode]100. Same Tree

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100. Same Tree

題目連結
難易度：Easy

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

思路

此題使用簡易遞回概念，先判斷p，q 空值狀況，若當前節點都為 null，也表示相同，最後 return left 和 right 子頁，如此遞回下去此 function，若 left, right 來做聯集即為答案。

解題

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/**
 * 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){
        if(!q){
            return true;
        }else{
            return false;
        }
    }
    if(!q){
        if(!p){
            return true;
        }else{
            return false;
        }    
    }
    if(p.val === q.val){
    }else{
        return false;
    }
    
    return isSameTree(p.left,q.left) && isSameTree(p.right,q.right);
    
};