对设置位等于K的数组元素进行排序

给定一个整数和一个数字数组$K$ 。任务是仅对总置位等于K的数组元素进行排序。排序必须仅在它们的相对位置进行，而不会影响任何其他元素。

例子：

Input : arr[] = {32, 1, 9, 4, 64, 2}, K = 1 
Output : 1 2 9 4 32 64
All of the elements except 9 has exactly 1 bit set.
So, all elements except 9 are sorted without affecting
the position of 9 in the input array.

Input : arr[] = {2, 15, 12, 1, 3, 9}, K = 2 
Output : 2 15 3 1 9 12

方法：

• 初始化两个空向量。
• 从左到右遍历数组，并检查每个元素的设置位。
• 在这里，C++内置函数__builtin_popcount()可以对setbit进行计数。
• 在第一个向量中，插入所有置位等于K的元素的索引。
• 在第二个向量中，插入置位等于K的元素。
• 排序第二个向量。
• 现在，我们将所有具有置位的元素的索引按排序顺序等于K，并将所有具有置位的元素的索引按排序顺序排序为K。
• 因此，将第二个向量的元素逐个插入到第一个向量中存在的索引处的数组中。

下面是上述方法的实现：

C++

// C++ program for sorting array elements
// with set bits equal to K
  
#include 
using namespace std;
  
// Function to sort elements with
// set bits equal to k
void sortWithSetbits(int arr[], int n, int k)
{
    // initialise two vectors
    vector v1, v2;
  
    for (int i = 0; i < n; i++) {
        if (__builtin_popcount(arr[i]) == k) {
  
            // first vector contains indices of
            // required element
            v1.push_back(i);
  
            // second vector contains 
            // required elements
            v2.push_back(arr[i]);
        }
    }
  
    // sorting the elements in second vector
    sort(v2.begin(), v2.end());
  
    // replacing the elements with k set bits
    // with the sorted elements
    for (int i = 0; i < v1.size(); i++)
        arr[v1[i]] = v2[i];
  
    // printing the new sorted array elements
    for (int i = 0; i < n; i++)
        cout << arr[i] << " ";
}
  
// Driver code
int main()
{
    int arr[] = { 14, 255, 1, 7, 13 };
    int n = sizeof(arr) / sizeof(arr[0]);
    int k = 3;
  
    sortWithSetbits(arr, n, k);
  
    return 0;
}

Java

// Java program for sorting array elements
// with set bits equal to K
import java.util.*;
  
// Represents node of a doubly linked list 
class Node 
{
  
    // Function to sort elements with
    // set bits equal to k
    static void sortWithSetbits(int arr[], int n, int k)
    {
        // initialise two vectors
        Vector v1 = new Vector<>(), v2 = new Vector<>();
  
        for (int i = 0; i < n; i++) {
            if (Integer.bitCount(arr[i]) == k) 
            {
  
                // first vector contains indices of
                // required element
                v1.add(i);
  
                // second vector contains 
                // required elements
                v2.add(arr[i]);
            }
        }
  
        // sorting the elements in second vector
        Collections.sort(v2);
  
        // replacing the elements with k set bits
        // with the sorted elements
        for (int i = 0; i < v1.size(); i++) 
        {
            arr[v1.get(i)] = v2.get(i);
        }
  
        // printing the new sorted array elements
        for (int i = 0; i < n; i++) 
        {
            System.out.print(arr[i] + " ");
        }
    }
  
    // Driver code
    public static void main(String[] args)
    {
        int arr[] = {14, 255, 1, 7, 13};
        int n = arr.length;
        int k = 3;
  
        sortWithSetbits(arr, n, k);
    }
}
  
// This code is contributed by Princi Singh

Python3

# Python 3 program for sorting array 
# elements with set bits equal to K
  
# Function to sort elements with
# set bits equal to k
def sortWithSetbits(arr, n, k):
      
    # initialise two vectors
    v1 = []
    v2 = []
  
    for i in range(0, n, 1):
        if (bin(arr[i]).count('1') == k):
              
            # first vector contains indices 
            # of required element
            v1.append(i)
  
            # second vector contains 
            # required elements
            v2.append(arr[i])
  
    # sorting the elements in second vector
    v2.sort(reverse = False)
  
    # replacing the elements with k set 
    # bits with the sorted elements
    for i in range(0, len(v1), 1):
        arr[v1[i]] = v2[i]
  
    # printing the new sorted array elements
    for i in range(0, n, 1):
        print(arr[i], end = " ")
  
# Driver code
if __name__ == '__main__':
    arr = [14, 255, 1, 7, 13]
    n = len(arr)
    k = 3
  
    sortWithSetbits(arr, n, k)
  
# This code is contributed by
# Surendra_Gangwar

C#

// C# program for sorting array elements
// with set bits equal to K
using System;
using System.Collections.Generic; 
  
// Represents node of a doubly linked list 
public class Node 
{
  
    // Function to sort elements with
    // set bits equal to k
    static void sortWithSetbits(int []arr, int n, int k)
    {
        // initialise two vectors
        List v1 = new List();
        List v2 = new List();
  
        for (int i = 0; i < n; i++) 
        {
            if (bitCount(arr[i]) == k) 
            {
  
                // first vector contains indices of
                // required element
                v1.Add(i);
  
                // second vector contains 
                // required elements
                v2.Add(arr[i]);
            }
        }
  
        // sorting the elements in second vector
        v2.Sort();
  
        // replacing the elements with k set bits
        // with the sorted elements
        for (int i = 0; i < v1.Count; i++) 
        {
            arr[v1[i]] = v2[i];
        }
  
        // printing the new sorted array elements
        for (int i = 0; i < n; i++) 
        {
            Console.Write(arr[i] + " ");
        }
    }
      
static int bitCount(long x)
{
    int setBits = 0;
    while (x != 0) 
    {
        x = x & (x - 1);
        setBits++;
    }
    return setBits;
} 
  
// Driver code
public static void Main(String[] args)
{
        int []arr = {14, 255, 1, 7, 13};
        int n = arr.Length;
        int k = 3;
  
        sortWithSetbits(arr, n, k);
}
}
  
/* This code is contributed by PrinciRaj1992 */

输出：

7 255 1 13 14