workshop

bitmask

package com.company;

public class Main {

    public static void main(String[] args) {

      oddeven(6);

      int[] ar ={1,1,5,2,2,6,6,7};
        System.out.println(uniqueno(ar));

        System.out.println(countsetbits(4));

        System.out.println(magicno(5));

        uniqueno2(ar);
    }

    public static void oddeven(int n){

        if((n&1)==1){
            System.out.println("odd");
        }
        else{
            System.out.println("even");
        }
    }

    public static int uniqueno( int[] ar){

        int res=0;

        for (int i = 0; i <ar.length ; i++) {

            res=res ^ar[i];
        }

        return res;
    }

    public static int countsetbits(int n){

        int cnt=0;

        while(n!=0){

            if((n&1)==1){
                cnt=cnt+1;
            }

            n=n>>1;
        }

        return cnt;
    }

    public static int magicno(int n){

        int pow = 1;
        int ans =0;

        while(n!=0){

            pow=pow*5;

            if((n&1)==1){
                ans= ans +pow;
            }
            n=n>>1;
        }

        return ans;
    }

    public static void uniqueno2(int[] ar){

        int res=0;

        for (int i = 0; i <ar.length ; i++) {

            res=res^ar[i];
        }

        int temp= res;

        int cnt=0;

        // this is to check the first rightmost set bit

        while(temp!=0){

            if((temp&1)==1){
                break;
            }

            cnt= cnt+1;
            temp = temp>>1;
        }


        int mask = 1<<cnt;

        int x=0;

        for (int i = 0; i <ar.length ; i++) {

            if((ar[i] & mask) >=1){
                x= x^ar[i];
            }
        }

        int y= x^res;

        System.out.println(x +" "+ y);
    }
}