#include <iostream>
#include <vector>
using namespace std;
 
int searchHelper(const int arr[], int start, int stop, int key)
{
	if(start == stop)	return -1;
	if(arr[start] == key) return start;
	return searchHelper(arr, start + 1, stop, key);
}
 
int search(const int arr[], int size, int key)
{
	return searchHelper(arr, 0, size, key);
}
 
int search(vector<int> const& vec, int key)
{
	return searchHelper(vec.data(), 0, (int)vec.size(), key);
}
 
int main() {
	int arr[] = {3,10,2,5,6,1};
 
	cout << search(arr, 6, 10) << endl;
	cout << search(arr, 6, 20) << endl;
 
	return 0;
}

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