Only bit operation is used to complete size comparison

How to judge without any comparison statement , You can return the larger of the two numbers

/** * @author  Yang Siyuan  * @version 1.0 * @title  Bit operation completes size comparison  * @date 2022/7/16 0:52 * @description  original   Not necessarily the optimal solution  a < b => -1 a == b => -1 a > b => 1 */
public class BitComparisonOfSize {
    

    //  Use only  !=
    public static int compare(int a, int b) {
    
        if (a >>> 31 != b >>> 31) return b >>> 31 - a >>> 31;
        for (int i = 30; i > 0; i--) {
    
            if (a >>> i != b >>> i) return a >>> i - b >>> i;
        }
        return 0;
    }

    //  Do not use any comparison statement  ( > < = != >= <= )
    public static int compare2(int a, int b) {
    
        return a - b >>> 31;
    }

    public static void main(String[] args) {
    
        System.out.println(" Beginning of the test ");
        for (int i = 0; i < 1000000; i++) {
    
            int a = (int) (Math.random() * Integer.MIN_VALUE) * Math.random() < 0.5 ? 1 : -1;
            int b = (int) (Math.random() * Integer.MIN_VALUE) * Math.random() < 0.5 ? 1 : -1;
            int res = compare(a, b);
            int res2 = compare2(a, b);
            int acceptedAnswer = Integer.compare(a, b);
            if (res != acceptedAnswer || res2 != acceptedAnswer) {
    
                System.out.println(" error ：a:" + a + ",b:" + b);
            }
        }
        System.out.println(" End of test ");
    }

}

Written in the back

Algorithm column ： Algorithm column

Application of more bit operations ：05. Simple application of bitmap and comparator

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