Find a number K such that exactly K array elements are greater than or equal to K
Given an array a[] of size N, which contains only non-negative elements, the task is to find any integer K for which there are exactly K array elements that are greater than or equal to K. If no such K exists, then print -1.
Examples:
Input: a[] = {7, 8, 9, 0, 0, 1}
Output: 3
Explanation:
Since 3 is less than or equal to 7, 8, and 9, therefore, 3 is the answer.Input: a[] = {0, 0}
Output: -1
Approach: The task is to find K such that the array elements are greater than or equal to K. Therefore, K cannot exceed the maximum element present in the array a[n]. Follow the steps below solve the problem:
- Traverse the array to find the largest array element, store it in a variable, say m.
- Initialize a counter variable, cnt to count the number of array elements greater than or equal to K.
- Iterate for possible values of K starting from 0 to m. Iterate over the array for each value and count the number of array elements greater than or equal to that value.
- If for any value, exactly K array elements are found to be greater than or equal to that value, print that value.
- If no such value is obtained after complete traversal of the array, print -1.
Below is the implementation of the above approach:
C++
// C++ program for the above approach#include <bits/stdc++.h>using namespace std;// Function to find K for which// there are exactly K array// elements greater than or equal to Kint zvalue(vector<int>& nums){ // Finding the largest array element int m = *max_element(nums.begin(), nums.end()); int cnt = 0; // Possible values of K for (int i = 0; i <= m; i++) { cnt = 0; // Traverse the array for (int j = 0; j < nums.size(); j++) { // If current array element is // greater than or equal to i if (nums[j] >= i) cnt++; } // If i array elements are // greater than or equal to i if (cnt == i) return i; } // Otherwise return -1;}// Driver Codeint main(){ vector<int> nums = { 7, 8, 9, 0, 0, 1 }; cout << zvalue(nums) << endl;} |
Java
// Java program for the above approachimport java.io.*;class GFG{// Function to find K for which// there are exactly K array// elements greater than or equal to Kpublic static int zvalue(int[] nums){ // Finding the largest array element int m = max_element(nums); int cnt = 0; // Possible values of K for(int i = 0; i <= m; i++) { cnt = 0; // Traverse the array for(int j = 0; j < nums.length; j++) { // If current array element is // greater than or equal to i if (nums[j] >= i) cnt++; } // If i array elements are // greater than or equal to i if (cnt == i) return i; } // Otherwise return -1;}// To find maximum Elementpublic static int max_element(int[] nums){ int max = nums[0]; for(int i = 1; i < nums.length; i++) max = Math.max(max, nums[i]); return max;}// Driver Codepublic static void main(String args[]){ int[] nums = { 7, 8, 9, 0, 0, 1 }; System.out.println(zvalue(nums));}}// This code is contributed by hemanth gadarla |
Python3
# Python3 program for the above approach# Function to find K for which# there are exactly K array# elements greater than or equal to Kdef zvalue(nums): # Finding the largest array element m = max(nums) cnt = 0 # Possible values of K for i in range(0, m + 1, 1): cnt = 0 # Traverse the array for j in range(0, len(nums), 1): # If current array element is # greater than or equal to i if (nums[j] >= i): cnt += 1 # If i array elements are # greater than or equal to i if (cnt == i): return i # Otherwise return -1# Driver Codeif __name__ == '__main__': nums = [ 7, 8, 9, 0, 0, 1 ] print(zvalue(nums)) # This code is contributed by SURENDRA_GANGWAR |
C#
// C# program for the// above approachusing System;class GFG{// Function to find K for which// there are exactly K array// elements greater than or equal to Kpublic static int zvalue(int[] nums){ // Finding the largest array element int m = max_element(nums); int cnt = 0; // Possible values of K for(int i = 0; i <= m; i++) { cnt = 0; // Traverse the array for(int j = 0; j < nums.Length; j++) { // If current array element is // greater than or equal to i if (nums[j] >= i) cnt++; } // If i array elements are // greater than or equal to i if (cnt == i) return i; } // Otherwise return -1;}// To find maximum Elementpublic static int max_element(int[] nums){ int max = nums[0]; for(int i = 1; i < nums.Length; i++) max = Math.Max(max, nums[i]); return max;}// Driver Codepublic static void Main(String []args){ int[] nums = {7, 8, 9, 0, 0, 1}; Console.WriteLine(zvalue(nums));}}// This code is contributed by 29AjayKumar |
Javascript
<script>// javascript program for the above approach// Function to find K for which// there are exactly K array// elements greater than or equal to Kfunction zvalue(nums){ // Finding the largest array element var m = max_element(nums); var cnt = 0; // Possible values of K for(i = 0; i <= m; i++) { cnt = 0; // Traverse the array for(j = 0; j < nums.length; j++) { // If current array element is // greater than or equal to i if (nums[j] >= i) cnt++; } // If i array elements are // greater than or equal to i if (cnt == i) return i; } // Otherwise return -1;}// To find maximum Elementfunction max_element(nums){ var max = nums[0]; for(i = 1; i < nums.length; i++) max = Math.max(max, nums[i]); return max;}// Driver Codenums = [ 7, 8, 9, 0, 0, 1 ]; document.write(zvalue(nums));// This code contributed by shikhasingrajput</script> |
Output:
3
Time Complexity: O(N2)
Auxiliary Space: O(1)
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