Checking Duplicates Numbers In Array c++ - c++

Question

I wrote a simple C++ program that finds how many duplicates are in the array.
This works perfectly for me but this is very long code. And I would like to know if there is any short code which may perform this task successfully:
#include<iostream>
using namespace std;
int main()
{
int a[10];
int reper=0,word=0,flage=0,number[10]={
0
};
//Getting Input From User
for (int i = 0; i <=9; i++)
{
cout<<"Enter The Value For "<<i<<" Index"<<endl;
cin>>a[i];
}
//Checking The Duplicates Numbers
for (int i = 0; i <= 9; i++)
{
reper=0;
flage=0;
for (int j = 0; j <=9; j++)
{
if (a[i]==a[j])
{
if (i!=j)
{
reper++;
}
}
}
number[i]=a[i];
for (int k = 0; k <=9; k++)
{
if (i!=k)
{
if(number[i]==number[k])
{
flage=1;
break;
}
}
}
//If There Are Duplicates Then Prints That Numebr, How Many Times It Repeated And Total Occurance Of That Number In The Array
if (reper!=0&&flage==0)
{
cout<<"Repeated Number Of The Array Is : "<<a[i]<<" ";
cout<<"And This Number Repeated "<<reper<<" Times "<<"And Total Occurance Of This Number is : "<<reper+1<<endl;
word=a[i];
}
}
//If There Is Nothing Any Duplicate In The Array Then Simply Prints This Message On Console
if (reper==0&&word==0)
{
cout<<"There Is Nothing Any Repeated Number Of This Array: "<<endl;
}
system("Pause");
return 0;
}

Answer 1

IMHO the easiest way to implement this - using http://en.cppreference.com/w/cpp/container/multiset. It has logarithmic complexity and inner methods to count repeated items.
Refer an example below:
#include <iostream>
#include <set>
int main(int argc, char *argv[])
{
std::multiset<int> ms;
//Getting Input From User
for (int i = 0; i <=9; i++)
{
std::cout<<"Enter The Value For "<<i<<" Index"<<std::endl;
int val;
std::cin>>val;
ms.insert(val);
}
bool repeated_number_found=false;
std::multiset<int>::const_iterator it = ms.begin();
while (it != ms.end()) {
int reper=ms.count(*it);
if (reper > 1){
std::cout << "Number " << *it << " repeated for " << reper << " times" << std::endl;
repeated_number_found=true;
}
it = ms.upper_bound(*it);
}
if (!repeated_number_found){
std::cout<<"There Is Nothing Any Repeated Number Of This Array"<<std::endl;
}
return 0;
}
But using this container you will loose first entrance of repeated number, if it matters to you, I will recommend using struct or std::pair to hold entrance number with entered number. In this case you will need to provide custom comparator also (refer to doc.)

Answer 2

I think the better way to achieve this would be to sort the array and do something like this :-
(include the header file algorithm before doing this.)
vector <int> a (10,0);
for (int i = 0; i <=9; i++)
{
cout<<"Enter The Value For "<<i<<" Index"<<endl;
cin>>a[i];
}
int count = 0;
sort(a.begin(), a.end());
for(int i = 0; i < a.size() - 1; i++) {
if (a[i] == a[i + 1]) {
count++;
}
}
cout << count << endl;