通过对数组元素的最近完全平方进行排序来修改数组，这些数组元素的数字按降序排序

给定一个大小为N ( 1 ≤ N ≤ 10 ⁵ ) 的数组arr[] ，任务是按降序对每个数组元素的数字进行排序，并将每个数组元素替换为最近的完全平方，然后按升序打印数组。

例子：

Input: arr[ ] = {29, 43, 28, 12}
Output: 25 49 81 100
Explanation:
Sorting digits of each array element in descending order modifies arr[] to {92, 43, 82, 21}.
Replacing elements with the nearest perfect square modifies arr[] to {100, 49, 81, 25}.
Sorting the array in ascending order modifies arr[] to {25, 49, 81, 100}.

Input: arr[ ] = {517, 142, 905}
Output: 441 729 961

处理方法：按照以下步骤解决问题：

• 遍历数组arr[] ，对每个数组元素进行如下操作。
  • 将它们转换为等效的字符串表示形式。
  • 按降序对字符串进行排序。
  • 将字符串转换回其等效整数。
  • 找到当前数组元素的最近的完美平方。
• 现在，按升序对数组进行排序。
• 打印排序后的数组。

下面是上述方法的实现。

C++

// C++ program of the above approach
 
#include 
using namespace std;
 
// Function to sort array in ascending order
// after replacing array elements by nearest
// perfect square of decreasing order of digits
void sortArr(int arr[], int N)
{
 
    // Traverse the array of strings
    for (int i = 0; i < N; i++) {
 
        // Convert the current array
        // element to a string
        string s = to_string(arr[i]);
 
        // Sort each string in descending order
        sort(s.begin(), s.end(), greater());
 
        // Convert the string to
        // equivalent integer
        arr[i] = stoi(s);
 
        // Calculate square root of
        // current array element
        int sr = sqrt(arr[i]);
 
        // Calculate perfect square
        int a = sr * sr;
        int b = (sr + 1) * (sr + 1);
 
        // Find the nearest perfect square
        if ((arr[i] - a) < (b - arr[i]))
            arr[i] = a;
        else
            arr[i] = b;
    }
 
    // Sort the array in ascending order
    sort(arr, arr + N);
 
    // Print the array
    for (int i = 0; i < N; i++) {
        cout << arr[i] << " ";
    }
}
 
// Driver Code
int main()
{
    int arr[] = { 29, 43, 28, 12 };
    int N = sizeof(arr) / sizeof(arr[0]);
    sortArr(arr, N);
 
    return 0;
}

Java

// Java program for the above approach
import java.util.*;
 
class GFG{
  static void reverse(char[] a) 
  {
    int i, n = a.length;
    char t;
    for (i = 0; i < n / 2; i++) 
    {
      t = a[i];
      a[i] = a[n - i - 1];
      a[n - i - 1] = t;
    }
  }
 
  // Function to sort array in ascending order
  // after replacing array elements by nearest
  // perfect square of decreasing order of digits
  static void sortArr(int arr[], int N)
  {
 
    // Traverse the array of strings
    for (int i = 0; i < N; i++) {
 
      // Convert the current array
      // element to a string
      String s = Integer.toString(arr[i]);
      char[] str = s.toCharArray();
 
      // Sort each string in descending order
      Arrays.sort(str);
      reverse(str);
 
      String string = new String(str);
 
 
      // Convert the string to
      // equivalent integer
      arr[i] = Integer.parseInt(string);
 
      // Calculate square root of
      // current array element
      int sr = (int)Math.sqrt(arr[i]);
 
      // Calculate perfect square
      int a = sr * sr;
      int b = (sr + 1) * (sr + 1);
 
      // Find the nearest perfect square
      if ((arr[i] - a) < (b - arr[i]))
        arr[i] = a;
      else
        arr[i] = b;
    }
 
    // Sort the array in ascending order
    Arrays.sort(arr);
 
    // Print the array
    for (int i = 0; i < N; i++) {
      System.out.print(arr[i] + " ");
    }
  }
 
 
  // Driver Code
  public static void main(String[] args)
  {
    int arr[] = { 29, 43, 28, 12 };
    int N = arr.length;
    sortArr(arr, N);
  }
}
 
// This code is contributed by sanjoy_62.

Python3

# Python 3 program of the above approach
import math
 
# Function to sort array in ascending order
# after replacing array elements by nearest
# perfect square of decreasing order of digits
def sortArr(arr, N):
 
    # Traverse the array of strings
    for i in range(N):
 
        # Convert the current array
        # element to a string
        s = str(arr[i])
 
        # Sort each string in descending order
        list1 = list(s)
        list1.sort(reverse = True)
        s = ''.join(list1)
 
        # Convert the string to
        # equivalent integer
        arr[i] = int(s)
 
        # Calculate square root of
        # current array element
        sr = int(math.sqrt(arr[i]))
 
        # Calculate perfect square
        a = sr * sr
        b = (sr + 1) * (sr + 1)
 
        # Find the nearest perfect square
        if ((arr[i] - a) < (b - arr[i])):
            arr[i] = a
        else:
            arr[i] = b
 
    # Sort the array in ascending order
    arr.sort()
 
    # Print the array
    for i in range(N):
        print(arr[i], end=" ")
 
# Driver Code
if __name__ == "__main__":
 
    arr = [29, 43, 28, 12]
    N = len(arr)
    sortArr(arr, N)
 
    # This code is contributed by ukasp.

C#

// C# program of the above approach
 
using System;
using System.Collections.Generic;
 
class GFG{
 
  // Function to sort array in ascending order
  // after replacing array elements by nearest
  // perfect square of decreasing order of digits
  static void sortArr(int []arr, int N)
  {
 
    // Traverse the array of strings
    for (int i = 0; i < N; i++) {
 
      // Convert the current array
      // element to a string
      int num = arr[i];
      string s = num.ToString();
 
      // Sort each string in descending order
      char []temp = s.ToCharArray();
      Array.Sort(temp);
      int st = 0;
      int ed = temp.Length-1;
      while(st());
 
      // Convert the string to
      // equivalent integer
      arr[i] = Int32.Parse(charsStr);
 
      // Calculate square root of
      // current array element
      int sr = (int)Math.Sqrt(arr[i]);
 
      // Calculate perfect square
      int a = sr * sr;
      int b = (sr + 1) * (sr + 1);
 
      // Find the nearest perfect square
      if ((arr[i] - a) < (b - arr[i]))
        arr[i] = a;
      else
        arr[i] = b;
    }
 
    // Sort the array in ascending order
    Array.Sort(arr);
 
    // Print the array
    for (int i = 0; i < N; i++) {
      Console.Write(arr[i]+" ");
    }
  }
 
  // Driver Code
  public static void Main()
  {
    int []arr = { 29, 43, 28, 12 };
    int N = arr.Length;
    sortArr(arr, N);
 
  }
}
 
// This code is contributed by ipg2016107.

Javascript

 
      // JavaScript program of the above approach
      // Function to sort array in ascending order
      // after replacing array elements by nearest
      // perfect square of decreasing order of digits
       
      function sortArr(arr, N) {
        // Traverse the array of strings
        for (var i = 0; i < N; i++) {
          // Convert the current array
          // element to a string
          var num = arr[i];
          var s = num.toString();
 
          // Sort each string in descending order
          var temp = s.split("");
          temp.sort((a, b) => b - a);
          s = temp.join("");
 
          // Convert the string to
          // equivalent integer
          arr[i] = parseInt(s);
 
          // Calculate square root of
          // current array element
          var sr = parseInt(Math.sqrt(arr[i]));
 
          // Calculate perfect square
          var a = sr * sr;
          var b = (sr + 1) * (sr + 1);
 
          // Find the nearest perfect square
          if (arr[i] - a < b - arr[i]) arr[i] = a;
          else arr[i] = b;
        }
 
        // Sort the array in ascending order
        arr.sort((a, b) => a - b);
 
        // Print the array
        for (var i = 0; i < N; i++) {
          document.write(arr[i] + " ");
        }
      }
 
      // Driver Code
      var arr = [29, 43, 28, 12];
      var N = arr.length;
      sortArr(arr, N);
       

输出：

25 49 81 100

时间复杂度： O(NlogN)
辅助空间： O(1)

如果您想与行业专家一起参加直播课程，请参阅Geeks Classes Live