leetcode 29. 两数相除

29. 两数相除

一、使用long类型

class Solution {
public:
    long divide2(long dividend,long divisor){
        if(dividend < 0 && divisor < 0)  return divide2(-dividend,-divisor);
        else if(dividend < 0 && divisor > 0)  return -divide2(-dividend,divisor);             
        else if(dividend > 0 && divisor < 0)  return -divide2(dividend,-divisor);
        if(divisor == 1) return dividend;
        if(dividend < divisor) return 0;
        long num = 0;
        while(dividend > 0){
            dividend -= divisor;
            num++;
        }
        if(dividend < 0)  return num-1;
        return num;
    }

    int divide(int dividend, int divisor) {
        long MAX = pow(2,31);
        long num = divide2(dividend,divisor);
        if(num > MAX-1)  return MAX-1;
        else if(num < -MAX)  return -MAX;
        return num;
    }
};

用时和消耗内存表现特别差