用 PHP 来刷leetCode 之 整数反转

题目:

方法一:反转字符串

class Solution {

    /**
     * @param Integer $x
     * @return Integer
     */
    function reverse($x) {
        $f = $x<0?true:false;
        $x = $f?abs($x):$x;
        $x = strval($x);
        
        $res = intval(strrev($x));
        $res = $f?-1*$res:$res;
        if(-2147483648<$res && 2147483647>$res){
            return $res;
        }else{
            return 0;
        }
    }
}

方法二:数学

<?php

class Solution {

    /**
     * @param Integer $x
     * @return Integer
     */
    function reverse($x) {
    	$val = abs($x);
    	if($val<10){
    		return $x;
    	}
    	$f = $x>0?false:true;
    	$num = 0;
        while($val>9){
            $res = $val%10;
            $val = floor($val/10);
            $num = $num*10+$res;
        }
        $num = $num*10+$val;
        if($f){
        	$num*=-1;
        }
        if(-2147483648<$num && 2147483647>$num){
            return $num;
        }else{
            return 0;
		}
    }
}

echo (new Solution)->reverse(-1246385);