fbhackercupparallelexecution.cpp

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ssize(x) int(x.size())
#define pb push_back
#define mp make_pair
#define all(a) begin(a),end(a)
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
#define FORR(x,arr) for(auto &x: arr)
#define REE(s_) {cout<<s_<<'\n';exit(0);}
#define GET(arr) for(auto &i: (arr)) sc(i)
#define e1 first
#define e2 second
#define INF 0x7f7f7f7f
#define debug(x...) cerr << "[" #x "]: ", [](auto... $) {((cerr << $ << "; "),...); }(x), cerr << '\n'
typedef std::pair<int,int> pi;
typedef std::vector<int> vi;
typedef std::vector<std::string> vs;
typedef int64_t ll;
typedef uint64_t ull;
using namespace std;
using namespace __gnu_pbds;

#ifdef ONLINE_JUDGE
#define debug(...) {}
#endif
#ifdef _WIN32
#define getchar_unlocked() _getchar_nolock()
#define _CRT_DISABLE_PERFCRIT_LOCKS
#endif
template<class A, class B> auto& operator<<(ostream &o, pair<A, B> p) { return o << '(' << p.first << ", " << p.second << ')'; }
template<class T> auto operator<<(ostream &o, T x) -> decltype(x.end(), o) { o << '{'; int i = 0; for(auto e : x) o << (", ")+2*!i++ << e; return o << '}'; }
inline int fstoi(const string &str){auto it=str.begin();bool neg=0;int num=0;if(*it=='-')neg=1;else num=*it-'0';++it;while(it<str.end()) num=num*10+(*it++-'0');if(neg)num*=-1;return num;}
inline void getch(char &x){while(x = getchar_unlocked(), x < 33){;}}
inline void getstr(string &str){str.clear(); char cur;while(cur=getchar_unlocked(),cur<33){;}while(cur>32){str+=cur;cur=getchar_unlocked();}}
template<typename T> inline bool sc(T &num){ bool neg=0; int c; num=0; while(c=getchar_unlocked(),c<33){if(c == EOF) return false;} if(c=='-'){ neg=1; c=getchar_unlocked(); } for(;c>47;c=getchar_unlocked()) num=num*10+c-48; if(neg) num*=-1; return true;}template<typename T, typename ...Args> inline void sc(T &num, Args &...args){ bool neg=0; int c; num=0; while(c=getchar_unlocked(),c<33){;} if(c=='-'){ neg=1; c=getchar_unlocked(); } for(;c>47;c=getchar_unlocked()) num=num*10+c-48; if(neg) num*=-1; sc(args...); }
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>; //s.find_by_order(), s.order_of_key() <- works like lower_bound
template<typename T> using ordered_map = tree<T, int, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
// 1 << 19 if segtree where merges matter.
#define N 1000001

struct tc {
    int n;
    /* vi a; */
    int res;
};
vector<tc> tcs;

void solve(int i){
    /* int n; */
    /* sc(n); */
    auto [n,_] = tcs[i];
    int res = 0;
    FOR(i,0,n-1){
        res += i;
    }
    tcs[i].res = res;
    /* cout << res << '\n'; */
}

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);
    int t;
    sc(t);
    REP(i,t){
        int n;
        sc(n);
        /* vi a(n); */
        /* GET(a) */
        tcs.push_back({n,-1});
    }
    int phases = 4; // Because can't start 1000 threads on students.
    int l = 0;
    REP(ph,phases){
        int rinc = t / phases + 1;
        std::thread ths[t];
        FOR(i,l,min(t,l+rinc)-1){
            debug(i);
            ths[i] = std::thread(solve, i);
        }
        FOR(i,l,min(t,l+rinc)-1)
            ths[i].join();
        l += rinc;
    }
    /* REP(i,t) */
    /*     solve(i); */
    // n = 100, 1e3:
    // pc: 0.920 vs 7.171 damn
    // students: 0.170 vs 4.625 damnnnn
    // -> czej, how is students cpu faster than mine? xd
    // mb compiler diff or sth.
    // -> older compiler, cpu only 2.2Ghz vs mine 3.*Ghz. hmm
    // anyway, ye, taktyk z użyciem studentsa def xd.
    /* while(t--){ */
    /*     solve(); */
    /* } */
    int it = 0;
    FORR(i,tcs){
        cout << "Case #" << it++ << ": " << i.res << '\n';
    }
}