swift leetcode-29 Divide Two Integers

题目链接：https://leetcode.com/problems/divide-two-integers/description/

题意：

• 给定连个整数，分别为dividend divisor,不使用乘除和mod运算求商
• 两个整数都被标记为32位
• 如果溢出则返回2^32 - 1

思路：

上来很懵逼，后来看了道长的思路，swift的bitwise operator的<<和>>来实现整体的位移

利用位移，将divisor翻倍，直到比dividentd大,得出位移次数temp，然后相减得出下一次循环的dividend。通过1<<(temp-1)得出十进制倍数

Solution

class Solution {
    func divide(_ dividend: Int, _ divisor: Int) -> Int {
        if divisor == 0 || (dividend == Int(Int32.min) && divisor == -1){
            return Int(Int32.max)
        }
        
        let isNagtive = (dividend < 0) != (divisor < 0)
        var dividend = abs(dividend)
        var divisor = abs(divisor)
        var temp = 0
        var count = 0
        while dividend >= divisor{
            var divisortemp = divisor
            temp = 0
            while dividend >= (divisortemp << temp){
                temp += 1
            }
            dividend -= divisor << (temp - 1)
            count += 1 << (temp - 1)
        }
        return isNagtive ? -count : count
    }
    
}