import java.util.Arrays;
/**
removeBitsAndShift(number, positions)
-------------------------------------
Removes multiple bit positions from a number and shifts the remaining bits
right to fill the gaps.
Important:
Bits must be removed from highest → lowest position.
Otherwise earlier removals shift the positions of later ones.
*/
public class Main {
public static int removeBitsAndShift(int number, int[] positions) {
// Sort positions descending
int[] sorted = Arrays.copyOf(positions, positions.length);
Arrays.sort(sorted);
for (int i = 0; i < sorted.length / 2; i++) {
int tmp = sorted[i];
sorted[i] = sorted[sorted.length - 1 - i];
sorted[sorted.length - 1 - i] = tmp;
}
int result = number;
for (int pos : sorted) {
int left = result >> (pos + 1); // bits above removed bit
int right = result & ((1 << pos) - 1); // bits below removed bit
result = (left << pos) | right; // merge
}
return result;
}
/**
printBinary(n)
--------------
Prints a 32-bit binary representation of an integer.
*/
public static void printBinary(int n) {
String binary = String.format("%32s", Integer.toBinaryString(n))
.replace(' ', '0');
// Group into 4-bit chunks
binary = binary.replaceAll("(.{4})", "$1 ");
System.out.println(binary);
}
public static void main(String[] args) {
int number = 1234; // 0000 0000 0000 0000 0000 0100 1101 0010
int[] positions = {1, 3, 7}; // remove bits 1, 3, 7 (0 = LSB)
System.out.println("Original number in binary:");
printBinary(number);
int result = removeBitsAndShift(number, positions);
System.out.println("\nNumber after removing bits {1, 3, 7} and shifting remaining bits:");
printBinary(result);
System.out.println("\nResult as integer: " + result);
}
}
/*
run:
Original number in binary:
0000 0000 0000 0000 0000 0100 1101 0010
Number after removing bits {1, 3, 7} and shifting remaining bits:
0000 0000 0000 0000 0000 0000 1001 0100
Result as integer: 148
*/
