Find the index of the element in an array which divides most elements before it
Given an array arr, the task is to find the index of the element in an array which divides most elements before it
Examples:
Input: arr = {5, 2, 1, 4, 5, 8, 2} Output: 6 Explanation arr[6] = 2 it divides 2, 4, and 8 (3 elements) Input: arr = {8, 1, 28, 4, 1, 6, 7} Output: 4
Approach:
- Maintain a map.
- For each arr[i] update the count variable by looking into map for ar[i] and insert all divisor of ar[i] into map.
- Update maxElement if cnt > maxx.
- Finally return the index with maxElement.
Below is the implementation of above approach:
CPP
// C++ program find the index of the element // in an array which divides // most elements before it #include <bits/stdc++.h> using namespace std; // Function to get the max element // divisible by arr[i] int maxElement( int arr[], int n) { map< int , int > mp; int maxx = -1, maxElement = -1; for ( int i = 0; i < n; i++) { int num = arr[i]; int cnt = 0; // Update count for A[i] if (mp.find(num) != mp.end()) { cnt += mp[num]; } // Generate Divisor For A[i] for ( int j = 1; j * j <= num; j++) { if (num % j == 0) { mp[j]++; if (j != num / j) mp[num / j]++; } } // Update Max Element if (cnt > maxx) { maxElement = i; maxx = cnt; } } return maxElement; } // Driver code int main() { int arr[] = { 5, 2, 1, 4, 5, 8, 2 }; int n = sizeof (arr) / sizeof (arr[0]); cout << maxElement(arr, n) << '\n' ; return 0; } |
Java
// Java program find the index of the element // in an array which divides // most elements before it import java.util.*; class GFG { // Function to get the max element // divisible by arr[i] static int maxElement( int arr[], int n) { HashMap<Integer, Integer> mp = new HashMap<Integer, Integer>(); int maxx = - 1 , maxElement = - 1 ; for ( int i = 0 ; i < n; i++) { int num = arr[i]; int cnt = 0 ; // Update count for A[i] if (mp.containsKey(num)) { cnt += mp.get(num); } // Generate Divisor For A[i] for ( int j = 1 ; j * j <= num; j++) { if (num % j == 0 ) { if (mp.containsKey(j)) mp.put(j, mp.get(j) + 1 ); else mp.put(j, 1 ); if (j != num / j) if (mp.containsKey(num / j)) mp.put(num / j, mp.get(num / j) + 1 ); else mp.put(num / j, 1 ); } } // Update Max Element if (cnt > maxx) { maxElement = i; maxx = cnt; } } return maxElement; } // Driver code public static void main(String[] args) { int arr[] = { 5 , 2 , 1 , 4 , 5 , 8 , 2 }; int n = arr.length; System.out.print(maxElement(arr, n)); } } // This code is contributed by 29AjayKumar |
Python
# Python3 program find the index of the element # in an array which divides # most elements before it # Function to get the max element # divisible by arr[i] def maxElement(arr, n): mp = dict () maxx = - 1 maxElement = - 1 for i in range (n): num = arr[i] cnt = 0 # Update count for A[i] if (num in mp): cnt + = mp[num] # Generate Divisor For A[i] j = 1 while j * j < = num: if (num % j = = 0 ): mp[j] = mp.get(j, 0 ) + 1 if (j ! = num / / j): mp[num / / j] = mp.get(num / / j, 0 ) + 1 j + = 1 # Update Max Element if (cnt > maxx): maxElement = i maxx = cnt return maxElement # Driver code arr = [ 5 , 2 , 1 , 4 , 5 , 8 , 2 ] n = len (arr) print (maxElement(arr, n)) # This code is contributed by mohit kumar 29 |
C#
// C# program find the index of the element // in an array which divides // most elements before it using System; using System.Collections.Generic; class GFG { // Function to get the max element // divisible by arr[i] static int maxElement( int []arr, int n) { Dictionary< int , int > mp = new Dictionary< int , int >(); int maxx = -1, maxElement = -1; for ( int i = 0; i < n; i++) { int num = arr[i]; int cnt = 0; // Update count for A[i] if (mp.ContainsKey(num)) { cnt += mp[num]; } // Generate Divisor For A[i] for ( int j = 1; j * j <= num; j++) { if (num % j == 0) { if (mp.ContainsKey(j)) mp[j] = mp[j] + 1; else mp.Add(j, 1); if (j != num / j) if (mp.ContainsKey(num / j)) mp[num / j] = mp[num / j] + 1; else mp.Add(num / j, 1); } } // Update Max Element if (cnt > maxx) { maxElement = i; maxx = cnt; } } return maxElement; } // Driver code public static void Main(String[] args) { int []arr = { 5, 2, 1, 4, 5, 8, 2 }; int n = arr.Length; Console.Write(maxElement(arr, n)); } } // This code is contributed by PrinciRaj1992 |
Javascript
<script> // JavaScript program find the index of the element // in an array which divides // most elements before it // Function to get the max element // divisible by arr[i] function maxElement(arr, n) { var mp = {}; var maxx = -1, maxElement = -1; for ( var i = 0; i < n; i++) { var num = arr[i]; var cnt = 0; // Update count for A[i] if (mp.hasOwnProperty(num)) { cnt += mp[num]; } // Generate Divisor For A[i] for ( var j = 1; j * j <= num; j++) { if (num % j === 0) { if (mp.hasOwnProperty(j)) mp[j] = mp[j] + 1; else mp[j] = 1; if (j !== num / j) if (mp.hasOwnProperty(num / j)) mp[num / j] = mp[num / j] + 1; else mp[num / j] = 1; } } // Update Max Element if (cnt > maxx) { maxElement = i; maxx = cnt; } } return maxElement; } // Driver code var arr = [5, 2, 1, 4, 5, 8, 2]; var n = arr.length; document.write(maxElement(arr, n)); // This code is contributed by rdtank. </script> |
Output:
6
Time Complexity: O(N?max(Arr))
Auxiliary Space: O(N) due to map data structure.
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