First Occurence using Recursion in C++

 #include <iostream>

#include <vector>

using namespace std;

int firstOccur(vector<int> arr, int i, int target) {

    if(i==arr.size()) {

        return -1;

    }

    if(arr[i] == target)

    {

        return i;

    }

    return firstOccur(arr, i+1, target);

}

int main() {

    vector<int> arr = {1, 2, 3, 3, 3, 4};

    cout << firstOccur(arr, 0, 4);

    return 0;

}