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 codeint 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 itimport 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 codearr = [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 itusing 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.