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Etsi saman todennäköisyyden esiintyvän elementin indeksi

Kun annettu kokonaislukutaulukko, etsi taulukon eniten esiintyvä elementti ja palauta mikä tahansa sen indekseistä satunnaisesti samalla todennäköisyydellä.
Esimerkkejä: 
 

  Input:    arr[] = [-1 4 9 7 7 2 7 3 0 9 6 5 7 8 9]   Output:    Element with maximum frequency present at index 6 OR Element with maximum frequency present at Index 3 OR Element with maximum frequency present at index 4 OR Element with maximum frequency present at index 12 All outputs above have equal probability.


 




Ajatuksena on iteroida taulukko kerran läpi ja selvittää suurin esiintyvä alkio ja sen taajuus n. Sitten generoimme satunnaisluvun r väliltä 1 ja n ja lopuksi palauttamme taulukon suurimman esiintyvän elementin r:nnen esiintymän.
Alla yllä olevan idean toteutus - 
 

C++
// C++ program to return index of most occurring element // of the array randomly with equal probability #include    #include  #include  using namespace std; // Function to return index of most occurring element // of the array randomly with equal probability void findRandomIndexOfMax(int arr[] int n) {  // freq store frequency of each element in the array  unordered_map<int int> freq;  for (int i = 0; i < n; i++)  freq[arr[i]] += 1;  int max_element; // stores max occurring element  // stores count of max occurring element  int max_so_far = INT_MIN;  // traverse each pair in map and find maximum  // occurring element and its frequency  for (pair<int int> p : freq)  {  if (p.second > max_so_far)  {  max_so_far = p.second;  max_element = p.first;  }  }  // generate a random number between [1 max_so_far]  int r = (rand() % max_so_far) + 1;  // traverse array again and return index of rth  // occurrence of max element  for (int i = 0 count = 0; i < n; i++)  {  if (arr[i] == max_element)  count++;  // print index of rth occurrence of max element  if (count == r)  {  cout << 'Element with maximum frequency present '  'at index ' << i << endl;  break;  }  } } // Driver code int main() {  // input array  int arr[] = { -1 4 9 7 7 2 7 3 0 9 6 5  7 8 9 };  int n = sizeof(arr) / sizeof(arr[0]);  // randomize seed  srand(time(NULL));  findRandomIndexOfMax(arr n);  return 0; } 
Java
// Java program to return index of most occurring element // of the array randomly with equal probability import java.util.*; class GFG { // Function to return index of most occurring element // of the array randomly with equal probability static void findRandomIndexOfMax(int arr[] int n) {  // freq store frequency of each element in the array  HashMap<Integer Integer> mp = new HashMap<Integer Integer>();  for (int i = 0; i < n; i++)  if(mp.containsKey(arr[i]))  {  mp.put(arr[i] mp.get(arr[i]) + 1);  }  else  {  mp.put(arr[i] 1);  }  int max_element = Integer.MIN_VALUE; // stores max occurring element  // stores count of max occurring element  int max_so_far = Integer.MIN_VALUE;  // traverse each pair in map and find maximum  // occurring element and its frequency  for (Map.Entry<Integer Integer> p : mp.entrySet())   {  if (p.getValue() > max_so_far)  {  max_so_far = p.getValue();  max_element = p.getKey();  }  }    // generate a random number between [1 max_so_far]  int r = (int) ((new Random().nextInt(max_so_far) % max_so_far) + 1);  // traverse array again and return index of rth  // occurrence of max element  for (int i = 0 count = 0; i < n; i++)  {  if (arr[i] == max_element)  count++;  // print index of rth occurrence of max element  if (count == r)  {  System.out.print('Element with maximum frequency present '  +'at index ' + i +'n');  break;  }  } } // Driver code public static void main(String[] args) {  // input array  int arr[] = { -1 4 9 7 7 2 7 3 0 9 6 5  7 8 9 };  int n = arr.length;  findRandomIndexOfMax(arr n); } } // This code is contributed by Rajput-Ji 
Python3
# Python3 program to return index of most occurring element # of the array randomly with equal probability import random # Function to return index of most occurring element # of the array randomly with equal probability def findRandomIndexOfMax(arr n): # freq store frequency of each element in the array mp = dict() for i in range(n) : if(arr[i] in mp): mp[arr[i]] = mp[arr[i]] + 1 else: mp[arr[i]] = 1 max_element = -323567 # stores max occurring element # stores count of max occurring element max_so_far = -323567 # traverse each pair in map and find maximum # occurring element and its frequency for p in mp : if (mp[p] > max_so_far): max_so_far = mp[p] max_element = p # generate a random number between [1 max_so_far] r = int( ((random.randrange(1 max_so_far 2) % max_so_far) + 1)) i = 0 count = 0 # traverse array again and return index of rth # occurrence of max element while ( i < n ): if (arr[i] == max_element): count = count + 1 # Print index of rth occurrence of max element if (count == r): print('Element with maximum frequency present at index '  i ) break i = i + 1 # Driver code # input array arr = [-1 4 9 7 7 2 7 3 0 9 6 5 7 8 9] n = len(arr) findRandomIndexOfMax(arr n) # This code is contributed by Arnab Kundu 
C#
using System; using System.Collections.Generic; class GFG { // Function to return index of most occurring element // of the array randomly with equal probability static void findRandomIndexOfMax(int[] arr int n) {  // freq store frequency of each element in the array  Dictionary<int int> mp = new Dictionary<int int>();  for (int i = 0; i < n; i++)  {  if (mp.ContainsKey(arr[i]))  {  mp[arr[i]]++;  }  else  {  mp[arr[i]] = 1;  }  }  int max_element = int.MinValue; // stores max occurring element  // stores count of max occurring element  int max_so_far = int.MinValue;  // traverse each pair in map and find maximum  // occurring element and its frequency  foreach (KeyValuePair<int int> p in mp)  {  if (p.Value > max_so_far)  {  max_so_far = p.Value;  max_element = p.Key;  }  }  // generate a random number between [1 max_so_far]  Random rand = new Random();  int r = rand.Next(max_so_far) + 1;  // traverse array again and return index of rth  // occurrence of max element  for (int i = 0 count = 0; i < n; i++)  {  if (arr[i] == max_element)  count++;  // print index of rth occurrence of max element  if (count == r)  {  Console.WriteLine('Element with maximum frequency present '  + 'at index ' + i + 'n');  break;  }  } } // Driver code public static void Main() {  // input array  int[] arr = { -1 4 9 7 7 2 7 3 0 9 6 5  7 8 9 };  int n = arr.Length;  findRandomIndexOfMax(arr n); } } 
JavaScript
<script> // Javascript program to return index of most occurring element // of the array randomly with equal probability // Function to return index of most occurring element // of the array randomly with equal probability function findRandomIndexOfMax(arrn) {  // freq store frequency of each element in the array  let mp = new Map();  for (let i = 0; i < n; i++)  if(mp.has(arr[i]))  {  mp.set(arr[i] mp.get(arr[i]) + 1);  }  else  {  mp.set(arr[i] 1);  }    let max_element = Number.MIN_VALUE; // stores max occurring element    // stores count of max occurring element  let max_so_far = Number.MIN_VALUE;    // traverse each pair in map and find maximum  // occurring element and its frequency  for (let [key value] of mp.entries())   {  if (value > max_so_far)  {  max_so_far = value;  max_element = key;  }  }    // generate a random number between [1 max_so_far]    let r = Math.floor(((Math.random() * max_so_far)% max_so_far)+ 1)    // traverse array again and return index of rth  // occurrence of max element  for (let i = 0 count = 0; i < n; i++)  {  if (arr[i] == max_element)  count++;    // print index of rth occurrence of max element  if (count == r)  {  document.write('Element with maximum frequency present '  +'at index ' + i +'  
'
); break; } } } // Driver code let arr=[-1 4 9 7 7 2 7 3 0 9 6 5 7 8 9 ]; let n = arr.length; findRandomIndexOfMax(arr n); // This code is contributed by avanitrachhadiya2155 </script>

Lähtö:  
 

Element with maximum frequency present at index 4


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