Chunk generate combinations for multi threaded combination generation

chunk-generate-combinations.rs

/*
 * n Number of elements in the pool
 * k Number of elements to choose for each combination, k <= n
 * init_index The starting index, init_index + k <= n
 */
fn chunk_generate_combinations(n: usize, k: usize, init_index: usize) {
    let mut indices: Vec<usize> = (init_index..init_index + k).collect();

    let k_sub_1 = k - 1;
    let n_sub_k = n - k;
    while indices[0] == init_index && indices[k_sub_1] < n {
        dbg!(&indices);

        // generate next combination in lexicographic order
        let mut t = k_sub_1;
        while t != 0 && indices[t] == n_sub_k + t {
            t -= 1;
        }
        indices[t] += 1;
        for j in t + 1..k {
            indices[j] = indices[j - 1] + 1;
        }
    }
}