力扣29. 两数相除

最新推荐文章于 2024-09-13 18:11:35 发布

原创最新推荐文章于 2024-09-13 18:11:35 发布 · 219 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#java

class Solution {
    public int divide(int dividend, int divisor) {
        if(divisor == 1) return dividend;
        if(divisor == -1 && dividend == Integer.MIN_VALUE){//Integer.MIN_VALUE
            return Integer.MAX_VALUE;
        }
        if(divisor < 0 && dividend < 0){
            return divide(-(long)dividend, -(long)divisor);
        }
        else if(dividend < 0 || divisor < 0){
            return -divide(Math.abs((long)dividend), Math.abs((long)divisor));//负号必须放前面
        }
        else return divide((long)dividend, (long)divisor);
    }

    public int divide(long dividend, long divisor){
        if (dividend < divisor) {
            return 0;
        }
        int count = 1;
        long sum = divisor;
        while(dividend >= sum){
            sum <<= 1;
            count <<= 1;
        }
        sum >>>= 1;//对正数而言，无符号和有符号右移没有区别
        count >>>= 1;//为什么是无符号右移
        return count + divide(dividend - sum, divisor);
    }
}