找不同

╰半夏微凉° 2022-12-29 01:41 112阅读 0赞

> leetcode 389题 \[easy\]  
> 中：[找不同][Link 1]  
> 英：[Find The Difference][]  
> ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1NKMTU1MQ_size_16_color_FFFFFF_t_70]![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1NKMTU1MQ_size_16_color_FFFFFF_t_70 1]

### 题解1 ###

##### 1. 思路：ASCII，求和，求差 #####

1.  两个字符串分别对各ASCII求和
2.  计算和值的差值

##### 2. 时间复杂度：O(n) #####

##### 3. 空间复杂度：O(1) #####

##### 4. 实现 #####

/** * @param {string} s * @param {string} t * @return {character} */
    var findTheDifference = function(s, t) { 
        let tSum = 0;
        for(let i=t.length-1; i>=0; i--){ 
            tSum += t.charCodeAt(i);
        }
        for(let i=s.length-1; i>=0; i--){ 
            tSum -= s.charCodeAt(i);
        }
        return String.fromCharCode([tSum]);
    };

### 题解2 ###

##### 1. 思路：ASCII，位运算，异或（找 s+t 拼接串中字符个数为奇数的字符） #####

1.  与[只出现一次的数字][Link 2]类似

##### 2. 时间复杂度：O(n) #####

##### 3. 空间复杂度：O(1) #####

##### 4. 实现 #####

/** * @param {string} s * @param {string} t * @return {character} */
    var findTheDifference = function(s, t) { 
        let xorSum = t.charCodeAt(0);
        for(let i=t.length-1; i>0; i--){ 
            xorSum ^= t.charCodeAt(i);
        }
        for(let i=s.length-1; i>=0; i--){ 
            xorSum ^= s.charCodeAt(i);
        }
        return String.fromCharCode(xorSum);
    };

[Link 1]: https://leetcode-cn.com/problems/find-the-difference/
[Find The Difference]: https://leetcode.com/problems/find-the-difference/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1NKMTU1MQ_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20201218175830995.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1NKMTU1MQ==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1NKMTU1MQ_size_16_color_FFFFFF_t_70 1]: /images/20221120/2398606a19c848b883c56255cc96e116.png
[Link 2]: https://blog.csdn.net/SJ1551/article/details/111386218