Most occurring element in an array using c++?

Question

I had tried the following code to get most occurring element in an array. It is working well but the only problem is when there are two or more elements having the same number of occurrence and equal to most occurring element, it just shows the first element scanned. Please help me through this.

#include <iostream>
using namespace std;
int main()
{
    int i,j,a[5];
    int popular = a[0];
    int temp=0, tempCount, count=1;
    cout << "Enter the elements: " << endl;
    for(i=0;i<5;i++)
        cin >> a[i];
    for (i=0;i<5;i++)
    {
        tempCount = 0;
        temp=a[i];
        tempCount++;
        for(j=i+1;j<5;j++)
        {
            if(a[j] == temp)
            {
                tempCount++;
                if(tempCount > count)
                {
                    popular = temp;
                    count = tempCount;
                }
            }
        }
    }
    cout << "Most occured element is: " <<  popular;
}

@Lakshayarora: how would you solve this using a genetic algorithm? — BlackBear, Oct 06 '13 at 14:41
Because you are a newbie, let me give you an advise: **Avoid `using namespace std;`**. Read [this thread](http://stackoverflow.com/questions/1452721/why-is-using-namespace-std-considered-bad-practice) to understand why is a bad practice. — Manu343726, Oct 06 '13 at 14:41
@Lakshayarora: that's a horrible advice to a beginner. how's that going to help him? — Karoly Horvath, Oct 06 '13 at 14:44
1st improve formatting! 2nd think over where you're going to declare your variables! — πάντα ῥεῖ, Oct 06 '13 at 14:45
@g-makulik What's wrong in variables' current places of declaration? — khajvah, Oct 06 '13 at 14:51
@khajvah Declaring the loop counter variable outside the loop declaration is usually a bad idea. — πάντα ῥεῖ, Oct 06 '13 at 14:54
@g-makulik ok, yeah, in case of `for` loop, there is no point to declare outside. — khajvah, Oct 06 '13 at 14:59

score 12 · Accepted Answer · edited Jun 05 '16 at 20:01

12

Repeat solution twice and change two line.

if (count>max_count)
    max_count = count;

with:

if (count==max_count)
    cout << a[i] << endl;

Solution:

int a[5];
for (int i=0;i<5;i++)
   cin>>a[i];

int max_count = 0;

for (int i=0;i<5;i++)
{
   int count=1;
   for (int j=i+1;j<5;j++)
       if (a[i]==a[j])
           count++;
   if (count>max_count)
      max_count = count;
}

for (int i=0;i<5;i++)
{
   int count=1;
   for (int j=i+1;j<5;j++)
       if (a[i]==a[j])
           count++;
   if (count==max_count)
       cout << a[i] << endl;
}

edited Jun 05 '16 at 20:01

answered Oct 06 '13 at 14:54

hasan

23,815
10
63
101

thanks @hasan this is the perfect solution for this program :) – Arun Pandey Oct 10 '13 at 12:36
Can you accept it as the answer to your question and upvote please :) – hasan Oct 10 '13 at 14:14
I tried but not having enough reputation . I would up vote after qualifying for it. – Arun Pandey Oct 13 '13 at 18:21
How could you make it choose the larger of the two when a tie occurs? – Breon Thibodeaux Oct 27 '16 at 03:35
@BreonThibodeaux the solution prints all those values. easliy you can modify the solution to only get the largest number. serach for max value on array. – hasan Oct 27 '16 at 12:12

score 3 · Answer 2 · answered Oct 06 '13 at 14:50

3

To collect all answers and not just the first one, you may use std::vector<int> popular instead of int popular.

then when tempCount == count, popular.push_back(temp);,

when tempCount > count, popular.clear(); popular.push_back(temp);

answered Oct 06 '13 at 14:50

Jarod42

203,559
14
181
302

score 1 · Answer 3 · answered Jan 31 '18 at 15:22

I think this solution will work better and it is shorter.

#include <iostream>
using namespace std;

int main()
{

int topCount=0, count, topElement, array[10];

for (int i=0 ; i<10 ; i++)
{
    cin>>array[i];
}

for ( int i=0 ; i<10 ;i++)
{
    count=0;
    for (int j=0 ; j<10 ; j++)
    {
        if (array[i]==array[j]) count++;
    }
    if (count>topCount)
    {
        topCount=count;
        topElement=array[i];
    }
}

cout<<topElement<<" "<<topCount;
}

score 0 · Answer 4 · answered Dec 20 '16 at 16:11

Here is a templatize solution:

template <class Iter, class ValType>
void findMostCommon_ (Iter first, Iter last)
{      
   typename std::vector<ValType> pop;
   int popular_cnt = 0;

   for (Iter it = first;   it != last;    ++it)
   {
      int temp_cnt = 0;

      for (Iter it2 = it + 1;  it2 != last;      ++it2)
         if (*it == *it2)
            ++temp_cnt;

      if (temp_cnt)
      {
         if (temp_cnt > popular_cnt)
         {
            popular_cnt = temp_cnt;
            pop.clear();
            pop.push_back(*it);
         }
         else if (temp_cnt == popular_cnt)
         {
            pop.push_back(*it);
         }
      }
   }

   if (pop.empty())  // all numbers unique
   {
      cout << "Could not find most popular" << endl;
   }
   else`enter code here`
   {
      cout << "Most popular numbers: ";

      for (typename std::vector<ValType>::const_iterator it = pop.begin(), lst = pop.end();   it != lst;    ++it)
         cout << (*it) << " ";
      cout << endl;
   }
}

It will get a list of most repeated numbers for any type of container that supports iterators including c-style arrays: Ex: — Ali Kayaten, Dec 20 '16 at 20:08

score 0 · Answer 5 · answered Nov 12 '18 at 20:28

Complete function for this type of problem:

int calcMode(int array[], int array_size)
{
int topCount=0, count, topElement = 10;

for ( int i=0 ; i<array_size ;i++)
{
    count=0;
    for (int j=0 ; j<array_size ; j++)
    {
        if (array[i]==array[j]) count++;
    }
    if (count>=topCount)
    {
        topCount=count;
        if (topElement > array[i])
            topElement=array[i];
    }
}

return topElement;
}

Most occurring element in an array using c++?

5 Answers5

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