LeetCode題解：Divide Two Integers

LeetCode題解：Divide Two Integers

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

If it is overflow, return MAX_INT.

題意：不使用乘，除，模符號作除法運算

解決思路：每一個數都可以用2進制表示，利用這一點通過位運算完成

代碼：

public class Solution {
    public int divide(int dividend, int divisor) {
        if(divisor == 0){
            return Integer.MAX_VALUE;
        }else if(divisor == 1){
            return dividend;
        }else if(divisor == -1){
            return dividend == Integer.MIN_VALUE ? Integer.MAX_VALUE : -dividend;
        }else{
            final int sign = ((dividend > 0 && divisor < 0) || (dividend < 0 && divisor > 0))? -1 : 1;

            long lDividend = Math.abs((long)dividend);
            long lDivisor = Math.abs((long)divisor);
            int result = 0;

            for(int i = Integer.SIZE - 1; i >= 0 && lDividend >= lDivisor; i--){
                if(lDividend >= (lDivisor << i)){
                    lDividend -= lDivisor << i;
                    result |= 1 << i;
                }
            }

            return result * sign;
        }
    }
}