Quick selection algorithm

gistfile1.cpp

int quick_find_kth(int *v, int n, int k) {
    if (n == 1 && k == 0) return v[0];

    int pivot = v[n-1];

    int store = 0;
    for (int i=0; i<n-1; i++) {
        if (v[i] < pivot) {
            swap(v[i], v[store++]);
        }
    }
    swap(v[store], v[n-1]);

    if (store == k) {
        return pivot;
    } else if (store > k) {
        return quick_find_kth(v, store, k);
    } else {
        return quick_find_kth(v+store+1, n-store-1, k-store-1);
    }
}