LeetCode -- Divide Two Integers

Divide Two Integers

题目描述
Divide two integers without using multiplication, division and mod operator.

If it is overflow, return MAX_INT.

整除两个整数，不能使用乘除，取模。

思路：
题目考的是位运算，求出除数的最大位移数max，使用被除数-1<<max，使用剩余的数继续计算。
注意特殊值的情况。

public class Solution {    public int Divide(int dividend, int divisor) {        if(dividend == 0){    return 0;    }    if(divisor == 0){    return dividend > 0 ? int.MaxValue : int.MinValue;    }        long x1 = dividend;    long x2 = divisor;    var negtive = false;    if(x1 < 0){    x1 = -x1;    negtive = !negtive;    }    if(x2 < 0){    x2 = -x2;    negtive = !negtive;    }        long result = 0;    long remain = x1;    while(remain >= x2)    {    var shifts = S(remain, x2);    remain -= x2 << shifts;    var v = 1<< shifts;    result += v;    //Console.WriteLine(remain + ","+ v);        }    if(negtive){    result = -result;    }            if(result < 0 && (result + int.MaxValue < 0)) //// less than int.MinValue    {    return int.MaxValue;    }        return (int)result;    }        private int S(long x, long y){    int count = -1;    while(x >= y){    x>>=1;    count ++;    }    return count;    }}