Divide Two Integers

最新推荐文章于 2021-05-07 19:18:17 发布

原创最新推荐文章于 2021-05-07 19:18:17 发布 · 2k 阅读

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本文介绍了一种特殊的整数除法算法，该算法能够在不使用乘法、除法及取模运算符的情况下实现两个整数相除。通过位移操作和累加实现了对除数的加倍直至超过被除数的过程，并逐步减去除数得到最终商的值。

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

public class Solution {
   public int divide(int dividend1, int divisor1) {
        if (divisor1 == 1) return dividend1;
        if (divisor1 == -1) return -dividend1;
        
        long dividend = dividend1;
		long divisor = divisor1;
    	
   	 	boolean isPositive = false; 
		 if (dividend > 0 && divisor > 0 || dividend < 0 && divisor < 0) {
			 isPositive = true;
		 }
		        
		dividend = Math.abs(dividend);
		divisor = Math.abs(divisor);
		 
		 if (dividend == 0) return 0;
		 int count = 1;
		 long current = divisor;
		 
		 while (current < dividend) {
			 count <<= 1;
			 current <<= 1;
		 }
		 
		 int result = 0;
		 while (current >= divisor) {
			 while (current <= dividend) {
				 dividend -= current;
				 result += count;
			 }
			 current >>= 1;
			 count >>= 1;
		 }
		if (isPositive == true) {
			return result;
		}
		return -result;
	 }
}