Given n, Returns a binary string that has been reversed. - Java java.lang

Java examples for java.lang:int Binary

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Description

Given n, Returns a binary string that has been reversed.

Demo Code


//package com.java2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        int n = 2;
        System.out.println(reverseBinary(n));
    }//  w  w  w  .  j  ava 2s  .co  m

    /**
     * Given n, Returns a binary string that has been reversed.
     * @param n
     * @return reversed binary number in integer
     * eg: 1101 -> 1011 ( which corresponds to number 11 )
     */
    public static int reverseBinary(int n) {
        int reversed = 0;

        int digits = getBinaryDigits(n);
        for (int i = digits - 1; i >= 0; i--) { // iterate from LHS of Var: reversed 
            if ((1 & n) == 1) {
                reversed = reversed | (1 << i); // Switch on bit to 1 from LHS  
            }

            n = (n >> 1);
        }

        return reversed;
    }

    /**
     * Returns amount of binary digits places if given integer n 
     * @param n 
     * @return number of binary digit places. ie, given n = 13, binary = 1101, 
     * number of binary places = 4 
     */
    public static int getBinaryDigits(int n) {
        if (n == 0 || n == 1)
            return 1;

        int k = 0;
        while (n - (1 << k) >= 0) {
            k++;
        }

        return k;
    }
}

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