LeetCode- Reverse Integer(JS题解)

Given a 32-bit signed integer, reverse digits of an integer.

Example 1:

Input: 123
Output: 321

Example 2:

Input: -123
Output: -321

Example 3:

Input: 120
Output: 21

Note:
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

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本体给出一个整数要求把整数反转，不过需要注意的是，反转整数的结果，正反符号需要保留且结果不在范围之内需返回零。

最先想到的方法：

思路：整数先转字符串，然后使用JS自带的反转函数进行字符串反转。反转后带上符号转成整数返回。提交后只有10%的超越率

/**
 * @param {number} x
 * @return {number}
 */
var reverse = function(x) {
    const isNegative=x<0;
    let result=(''+Math.abs(x)).split('').reverse().join('');
    result=isNegative?'-'+result:result;
    result=parseInt(result);
    if(result<-2147483648||result>2147483647){return 0;}
    return result;
};

取余：
思路：对一个整数不断的取余。

/**
 * @param {number} x
 * @return {number}
 */
var reverse = function(x) {
    const isNegative=x<0;
    x=Math.abs(x);
    let result=''
    while(x){
        const remainder=x%10;
        result+=(remainder);
        x=Math.floor(x/10);   
    }
    result =isNegative?'-'+result:result;
    if(result<-2147483648||result>2147483647){return 0;}
    return Math.floor(result);
};