g0001_0100.s0029_divide_two_integers.Solution Maven / Gradle / Ivy

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package g0001_0100.s0029_divide_two_integers;

// #Medium #Top_Interview_Questions #Math #Bit_Manipulation #Udemy_Bit_Manipulation
// #2022_06_14_Time_1_ms_(99.96%)_Space_39.6_MB_(87.25%)

/**
 * 29 - Divide Two Integers\.
 *
 * Medium
 *
 * Given two integers `dividend` and `divisor`, divide two integers **without** using multiplication, division, and mod operator.
 *
 * The integer division should truncate toward zero, which means losing its fractional part. For example, `8.345` would be truncated to `8`, and `-2.7335` would be truncated to `-2`.
 *
 * Return _the **quotient** after dividing_ `dividend` _by_ `divisor`.
 *
 * **Note:** Assume we are dealing with an environment that could only store integers within the **32-bit** signed integer range: [−2³¹, 2³¹ − 1]. For this problem, if the quotient is **strictly greater than** [2³¹ − 1], then return [2³¹ − 1], and if the quotient is **strictly less than** [-2³¹ − 1], then return [-2³¹ − 1].
 *
 * **Example 1:**
 *
 * **Input:** dividend = 10, divisor = 3
 *
 * **Output:** 3
 *
 * **Explanation:** 10/3 = 3.33333.. which is truncated to 3. 
 *
 * **Example 2:**
 *
 * **Input:** dividend = 7, divisor = -3
 *
 * **Output:** -2
 *
 * **Explanation:** 7/-3 = -2.33333.. which is truncated to -2. 
 *
 * **Example 3:**
 *
 * **Input:** dividend = 0, divisor = 1
 *
 * **Output:** 0 
 *
 * **Example 4:**
 *
 * **Input:** dividend = 1, divisor = 1
 *
 * **Output:** 1 
 *
 * **Constraints:**
 *
 * *   -2³¹ <= dividend, divisor <= 2³¹ - 1
 * *   `divisor != 0`
**/
public class Solution {
    public int divide(int dividend, int divisor) {
        boolean isNegative = dividend > 0 && divisor < 0 || dividend < 0 && divisor > 0;
        long ans = 0;
        long divide = Math.abs((long) dividend);
        long divisorAbs = Math.abs((long) divisor);
        while (divide >= divisorAbs) {
            long temp = divisorAbs;
            long cnt = 1;
            while (divide >= temp) {
                divide -= temp;
                ans += cnt;
                cnt <<= 1;
                temp <<= 1;
            }
        }
        if (isNegative) {
            ans = -ans;
        }
        int intMin = -(1 << 31);
        int intMax = (1 << 31) - 1;
        if (ans < intMin || ans > intMax) {
            ans = intMax;
        }
        return (int) ans;
    }
}