29. 两数相除 leetcode

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class Solution {
    func divide(_ dividend: Int, _ divisor: Int) -> Int {
        if dividend == 0{
            return 0;
        }
        var isNeed = false
        var dividend = dividend;
        var divisor = divisor;
        if dividend > 0 && divisor < 0{
            isNeed = true
            divisor = 0 - divisor;
        }else if dividend < 0 && divisor > 0{
            isNeed = true
            dividend = 0 - dividend;
        }else if dividend < 0 && divisor < 0{
            divisor = 0 - divisor;
            dividend = 0 - dividend;
        }
        if divisor == 1{
            
            if isNeed {
                return Int(Int32(0 - dividend));
            }else{
                if dividend >= 2^31{
                    return Int(Int32.max)
                }
                return Int(Int32(dividend));
            }
        }
        var i = 0;
        while divisor <= dividend {
            var temp = divisor;
            var cnt = 1;
            while dividend >= temp{
                temp = temp<<1
                cnt = cnt<<1
            }
            i += (cnt>>1)
            dividend -= (temp>>1)
        }
        if isNeed {
            return Int(0 - i);
        }else{
            return Int(i);
        }
    }
}