Formula to generate index of element of array after k insertions

rotationidx.cpp

#include <iostream>
using namespace std;

// returns the element at index m in arr after k rotations
int at(int* arr, int n, int k, int m) {
    return arr[((m + (n - (k % n))) % n)];
}

int main() {
    int n, k, q, i, j, m;
    int* arr;
    cin >> n >> k >> q;
    
    arr = new int[n];
    for (i = 0; i < n; ++i)
        cin >> arr[i];
    
    for (j = 0; j < q; ++j) {
        cin >> m;
        cout << at(arr, n, k, m) << '\n';
    }
    
    return 0;
}