不使用 *、/、+、

本文介绍了不使用 *、/、+、-、% 运算符将数字除以 3的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

如果不使用*、/、+、-、%，运算符?

How would you divide a number by 3 without using *, /, +, -, %, operators?

该号码可能有符号或无符号.

The number may be signed or unsigned.

推荐答案

这是一个简单函数，执行所需操作.但它需要 + 运算符，所以你剩下要做的就是用位运算符添加值:

This is a simple function which performs the desired operation. But it requires the + operator, so all you have left to do is to add the values with bit-operators:

// replaces the + operator int add(int x, int y) { while (x) { int t = (x & y) << 1; y ^= x; x = t; } return y; } int divideby3(int num) { int sum = 0; while (num > 3) { sum = add(num >> 2, sum); num = add(num >> 2, num & 3); } if (num == 3) sum = add(sum, 1); return sum; }

正如吉姆所说，这是可行的，因为:

As Jim commented this works, because:

• n = 4 * a + b
• n/3 = a + (a + b)/3

• 所以sum += a，n = a + b，然后迭代

当a == 0 (n <4), sum += floor(n/3); 即1, if n== 3，否则为 0