source.cpp
#include "functions.h"

int main(){
	Table BeforeSort;												// create table
	int Counter=100;												// how many numbers there is in single table
	BeforeSort.array = new int[Counter];
	BeforeSort.BasicFunctions(Counter);								// generate random numbers, sort, and print
	std::cout << "==================================\n";			// break line
	Table AfterSort;												// new table
	AfterSort.array = new int[Counter / 2];							// worst scenario
	int RepeatsCounter = 0;
	DetectRepeats(BeforeSort.array, AfterSort.array, Counter,RepeatsCounter);
	AfterSort.PrintTable(AfterSort.array,RepeatsCounter);
	std::cout << RepeatsCounter << " numbers repeat.";
	delete[]BeforeSort.array;
	delete[]AfterSort.array;
	return 0;
}

functions.h
#pragma once
#include <iostream>
#include <stdlib.h>																// RNG
#include <time.h>

class Table {
public:
	int* array=nullptr;															// table pointer
	void Sort(int* TablePointer, int TableElementCounter);
	void GetRandomFill(int* TablePointer, int TableElementCounter);
	void PrintTable(int *TablePointer, int TableElementCounter);
	void BasicFunctions(int Counter) {											// summarize these 3 functions
		GetRandomFill(array, Counter);
		Sort(array, Counter);
		PrintTable(array, Counter);
	}
};

void DetectRepeats(int* OldTablePointer,int *array, int TableCounter,int &j);

functions.cpp
#include "functions.h"

void Swap(int* a, int* b) {																	// swap 2 numbers
	int c;
	c = *a;
	*a = *b;
	*b = c;
}																																							// swap 2 numbers

void Table::Sort(int* TablePointer, int TableElementCount) {								// bubble sort
	for (int j = 0; j < TableElementCount; j++)
		for (int i = 0; i < TableElementCount - j; i++)
			if (TablePointer[i] < TablePointer[i+1])
				Swap(TablePointer + i, TablePointer + i + 1);
}

void Table::GetRandomFill(int* TablePointer, int TableElementCounter) {						// rng table fill
	srand(time(NULL));
	for (int i = 0; i < TableElementCounter; i++)
		TablePointer[i] = rand() % 150;
}

void Table::PrintTable(int* TablePointer, int TableElementCounter) {
	for (int i = 0; i < TableElementCounter; i++)
		std::cout << TablePointer[i] << std::endl;
}

void DetectRepeats(int* OldTablePointer,int *Array,int TableCounter, int &j) {				// if next 2 numbers are the same, they repeat
	for (int i = 0; i < TableCounter ; i++)
		if (OldTablePointer[i] == OldTablePointer[i + 1]&&Array[j-1]!=OldTablePointer[i]) {
			Array[j] = OldTablePointer[i];
			j++;
		}
}