Given an array arr[], the task is to count the maximum number of elements that can be selected from the given array following the below selection process:
- At 1st selection, select an element which is greater than or equal to 1.
- At 2nd selection, select an element which is greater than or equal to 2.
- At 3rd selection, select an element which is greater than or equal to 3 and so on.
An element can be selected only once. The operation stops when it is not possible to select any element. So, the task is to maximize the count of selection from the array.
Examples:
Input : arr[] = { 4, 1, 3, 1 }
Output : 3
1st Selection: 1 is selected as 1 >= 1.
2nd Selection: 3 is selected as 3 >= 2.
3rd Selection: 4 is selected as 4 >= 3.
No more selections are possible. Therefore, the answers is 3.Input : arr[] = { 2, 1, 1, 2, 1 }
Output : 2
Approach: In order to maximize the count of selection it is necessary to select the smallest possible numbers first and then the bigger numbers if the selection is not possible. This can be done easily by sorting the array. Now, loop through the array and increment the result by 1 when the element is greater than or equal to the number to select for the current operation.
Below is the implementation of the above approach:
C++
// C++ implementation of the approach#include <bits/stdc++.h>using namespace std;// Function to return the maximum count of // selection possible from the given array // following the given processint maxSelectionCount(int a[], int n){ // Initialize result int res = 0; // Sorting the array sort(a, a + n); // Initialize the select variable int select = 1; // Loop through array for (int i = 0; i < n; i++) { // If selection is possible if (a[i] >= select) { res++; // Increment result select++; // Increment selection variable } } return res;}// Driver Codeint main(){ int arr[] = { 4, 2, 1, 3, 5, 1, 4 }; int N = sizeof(arr) / sizeof(arr[0]); cout << maxSelectionCount(arr, N); return 0;} |
Java
// Java implementation of the approachimport java.util.*;class GFG { // Function to return the maximum count of // selection possible from the given array // following the given process static int maxSelectionCount(int a[], int n) { // Initialize result int res = 0; // Sorting the array Arrays.sort(a); // Initialize the select variable int select = 1; // Loop through array for (int i = 0; i < n; i++) { // If selection is possible if (a[i] >= select) { res++; // Increment result select++; // Increment selection variable } } return res; } // Driver Code public static void main(String[] args) { int arr[] = {4, 2, 1, 3, 5, 1, 4}; int N = arr.length; System.out.println(maxSelectionCount(arr, N)); }}// This code contributed by Rajput-Ji |
Python3
# Python implementation of the approach# Function to return the maximum count of # selection possible from the given array # following the given processdef maxSelectionCount(a, n): # Initialize result res = 0; # Sorting the array a.sort(); # Initialize the select variable select = 1; # Loop through array for i in range(n): # If selection is possible if (a[i] >= select): res += 1; # Increment result select += 1; # Increment selection variable return res;# Driver Codearr = [ 4, 2, 1, 3, 5, 1, 4 ];N = len(arr);print(maxSelectionCount(arr, N));# This code contributed by PrinciRaj1992 |
C#
// C# implementation of the approach using System;class GFG { // Function to return the maximum count of // selection possible from the given array // following the given process static int maxSelectionCount(int []a, int n) { // Initialize result int res = 0; // Sorting the array Array.Sort(a); // Initialize the select variable int select = 1; // Loop through array for (int i = 0; i < n; i++) { // If selection is possible if (a[i] >= select) { res++; // Increment result select++; // Increment selection variable } } return res; } // Driver Code public static void Main() { int []arr = {4, 2, 1, 3, 5, 1, 4}; int N = arr.Length; Console.WriteLine(maxSelectionCount(arr, N)); } } // This code contributed by AnkitRai01 |
Javascript
<script>// Javascript implementation of the approach// Function to return the maximum count of // selection possible from the given array // following the given processfunction maxSelectionCount(a, n){ // Initialize result var res = 0; // Sorting the array a.sort(); // Initialize the select variable var select = 1; // Loop through array for(var i = 0; i < n; i++) { // If selection is possible if (a[i] >= select) { // Increment result res++; // Increment selection variable select++; } } return res;}// Driver Codevar arr = [ 4, 2, 1, 3, 5, 1, 4 ];var N = arr.length;document.write(maxSelectionCount(arr, N));// This code is contributed by rrrtnx</script> |
5
Time Complexity: O(N * log(N))
Auxiliary Space: O(1)
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