Hackerrank Java BitSet Solution

Java's BitSet class implements a vector of bit values (i.e.:  () or  ()) that grows as needed, allowing us to easily manipulate bits while optimizing space (when compared to other collections). Any element having a bit value of  is called a set bit.

Given  BitSets,  and , of size  where all bits in both BitSets are initialized to , perform a series of  operations. After each operation, print the number of set bits in the respective BitSets as two space-separated integers on a new line.

Input Format

The first line contains  space-separated integers,  (the length of both BitSets  and ) and  (the number of operations to perform), respectively.
The  subsequent lines each contain an operation in one of the following forms:

• AND
• OR
• XOR
• FLIP
• SET

In the list above,  is the integer  or , where  denotes  and  denotes .
is an integer denoting a bit's index in the BitSet corresponding to .

For the binary operations , , and , operands are read from left to right and the BitSet resulting from the operation replaces the contents of the first operand. For example:

AND 2 1

is the left operand, and  is the right operand. This operation should assign the result of  to .

Constraints

Output Format

After each operation, print the respective number of set bits in BitSet  and BitSet  as  space-separated integers on a new line.

Sample Input

5 4
AND 1 2
SET 1 4
FLIP 2 2
OR 2 1

Sample Output

0 0
1 0
1 1
1 2

Explanation

Initially: , , , and . At each step, we print the respective number of set bits in  and  as a pair of space-separated integers on a new line.

,  
The number of set bits in  and  is .

Set  to  ().
, .
The number of set bits in  is  and  is .

Flip  from  () to  ().
, .
The number of set bits in  is  and  is .

.
, .
The number of set bits in  is  and  is .

Solution in java8

Approach 1.

import java.io.*;
import java.util.*;

public class Solution {
public static void main(String[] args) {
        Scanner get = new Scanner(System.in);
        int n = get.nextInt();
        int m = get.nextInt();
      
        BitSet b1 = new BitSet(n);
        BitSet b2 = new BitSet(n);
        BitSet[] bitset = new BitSet[3];
      
        bitset[1] = b1;
        bitset[2] = b2;
      
        while ( 0 < m-- ) {
          String op = get.next();
          int x = get.nextInt();
          int y = get.nextInt();
          
          switch (op) {
            case "AND":
              bitset[x].and(bitset[y]);
              break;
            case "OR":
              bitset[x].or(bitset[y]);
              break;
            case "XOR":
              bitset[x].xor(bitset[y]);
              break;
            case "FLIP":
              bitset[x].flip(y);
              break;
            case "SET":
              bitset[x].set(y);
          }
          
          System.out.printf("%d %d%n", b1.cardinality(), b2.cardinality());
        }
    }
}

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Approach 2.

import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
     Scanner get = new Scanner(System.in);
        int n = get.nextInt();
        int m = get.nextInt();
      
        BitSet b1 = new BitSet(n);
        BitSet b2 = new BitSet(n);
        BitSet[] bitset = new BitSet[3];
      
        bitset[1] = b1;
        bitset[2] = b2;
      
        while ( 0 < m-- ) {
          String op = get.next();
          int x = get.nextInt();
          int y = get.nextInt();
          
          switch (op) {
            case "AND":
              bitset[x].and(bitset[y]);
              break;
            case "OR":
              bitset[x].or(bitset[y]);
              break;
            case "XOR":
              bitset[x].xor(bitset[y]);
              break;
            case "FLIP":
              bitset[x].flip(y);
              break;
            case "SET":
              bitset[x].set(y);
          }
          
          System.out.printf("%d %d%n", b1.cardinality(), b2.cardinality());
        } 
    }
}

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Approach 3.

import java.util.BitSet;
import java.util.Scanner;

public class Solution {

    public static void main(String[] args) {
        Scanner get = new Scanner(System.in);
        int n = get.nextInt();
        int m = get.nextInt();
      
        BitSet b1 = new BitSet(n);
        BitSet b2 = new BitSet(n);
        BitSet[] bitset = new BitSet[3];
      
        bitset[1] = b1;
        bitset[2] = b2;
      
        while ( 0 < m-- ) {
          String op = get.next();
          int x = get.nextInt();
          int y = get.nextInt();
          
          switch (op) {
            case "AND":
              bitset[x].and(bitset[y]);
              break;
            case "OR":
              bitset[x].or(bitset[y]);
              break;
            case "XOR":
              bitset[x].xor(bitset[y]);
              break;
            case "FLIP":
              bitset[x].flip(y);
              break;
            case "SET":
              bitset[x].set(y);
          }
          
          System.out.printf("%d %d%n", b1.cardinality(), b2.cardinality());
        }
    }
}

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