Prime Cuts || UVA

#include <bits/stdc++.h>
#define max 9000
#define pb push_back
#define pairs pair<int, int>
#define vi vector<int>
#define vb vector<bool>
#define vii vector<pairs>
#define lb lower_bound
#define ub upper_bound
#define lli long long int
#define endl '\n'
using namespace std;

bool isPrime[max];
vi Prime;
vi output;

void sieve() {
    memset(isPrime, true, sizeof(isPrime));     // first all odd number's prime

    isPrime[0] = 0;

    // Sieve
    for (int i = 2; i * i <= max; i++) {
        if(isPrime[i]) {
            for (int j = i * i; j <= max; j += i) {
                isPrime[j] = 0;
            }
        }
    }
}


int middle(int n) {
    return n / 2;
}

void handleEven(int c, int mid) {
    int count = 0;
    int index = mid;
    output.push_back(Prime[mid]);
    while(true) {
        if(count == c - 1) {
            break;
        }
        output.push_back(Prime[++index]);
        count++;
    }
    count = 0;
    index = mid;
    while(true) {
        if(count == c) {
            break;
        }
        output.push_back(Prime[--index]);
        count++;
    }
}

void handleOdd(int c, int mid) {
    int count = 0;
    int index = mid;
    output.push_back(Prime[mid]);
    while(true) {
        if(count == c - 1) {
            break;
        }
        output.push_back(Prime[++index]);
        count++;
    }
    count = 0;
    index = mid;
    while(true) {
        if(count == c - 1) {
            break;
        }
        output.push_back(Prime[--index]);
        count++;
    }
}

void print(int n, int c) {
    cout << n << " " << c << ":";
    if(n == 1) {
        cout << " " << 1 << endl;
    } else {
        for (int i : output) {
            if(i < Prime[n])
                cout << " " << i;
        }
        cout << endl;
    }
}


int main() {
#ifndef Niloy
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    sieve();
    for (int i = 0; i <= max; i++) {
        if(isPrime[i] == 1) {
            Prime.push_back(i);
        }
    }

    int n, c, length;

    while(cin >> n >> c) {
        output.clear();
        length = 0;
        for (int i = 0; i < n; i++) {
            if(Prime[i] <= n) {
                length++;
            }
        }
        int mid = middle(length);
        if(n == 1) {
            print(n, c);
        } else {
            if(length < c) {
                for (int i = 0; i < length; i++) {
                    output.push_back(Prime[i]);
                }
            } else if(length % 2 == 0) {
                handleEven(c, mid);
            } else {
                handleOdd(c, mid);
            }
            sort(output.begin(), output.end());
            print(n, c);
        }
        cout << endl;
        output.clear();
    }

    return 0;
}