leetcode - 29.Divide Two Integers

最新推荐文章于 2024-04-23 07:08:59 发布

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本文介绍了一种不使用乘法、除法和取模运算符实现整数除法的方法。通过位移操作来逐步逼近商的值，并考虑了溢出的情况。

Divide Two Integers

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

If it is overflow, return MAX_INT.

Solution:

  public int divide(int dividend, int divisor) {
    int flag = (dividend < 0 && divisor > 0) || (dividend > 0 && divisor < 0) ? -1 : 1;
    long ldividend = Math.abs((long) dividend);
    long ldivisor = Math.abs((long) divisor);

    if (ldividend == 0 || (ldividend < ldivisor)) {
      return 0;
    }

    long lresult = ldivide(ldividend, ldivisor);

    int result;
    if (lresult > Integer.MAX_VALUE) {
      result = (flag == 1) ? Integer.MAX_VALUE : Integer.MIN_VALUE;
    } else {
      result = (int) (flag * lresult);
    }

    return result;
  }

  private long ldivide(long ldividend, long ldivisor) {
    if (ldividend < ldivisor)
      return 0;

    long sum = ldivisor;
    long multiple = 1;
    while ((sum << 1) <= ldividend) {
      sum <<= 1;
      multiple <<= 1;
    }
    return multiple + ldivide(ldividend - sum, ldivisor);
  }