제출 #254644

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
254644		MarcoMeijer	Triangles (CEOI18_tri)	C++14	0 / 100	1 ms	512 KiB

tri

#include <bits/stdc++.h>
#include "trilib.h"
using namespace std;

// macros
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ll, ll> lll;
typedef tuple<int, int, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<iii> viii;
typedef vector<ll> vll;
typedef vector<lll> vlll;
#define REP(a,b,c) for(int a=int(b); a<int(c); a++)
#define RE(a,c) REP(a,0,c)
#define RE1(a,c) REP(a,1,c+1)
#define REI(a,b,c) REP(a,b,c+1)
#define REV(a,b,c) for(int a=int(c-1); a>=int(b); a--)
#define FOR(a,b) for(auto& a : b)
#define all(a) a.begin(), a.end()
#define INF 1e9
#define EPS 1e-9
#define pb push_back
#define popb pop_back
#define fi first
#define se second
#define sz size()
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

// input
template<class T> void IN(T& x) {cin >> x;}
template<class H, class... T> void IN(H& h, T&... t) {IN(h); IN(t...); }

// output
template<class T1, class T2> void OUT(const pair<T1,T2>& x);
template<class T> void OUT(const T& x) {cout << x;}
template<class H, class... T> void OUT(const H& h, const T&... t) {OUT(h); OUT(t...); }
template<class T1, class T2> void OUT(const pair<T1,T2>& x) {OUT(x.fi," ",x.se);}
template<class... T> void OUTL(const T&... t) {OUT(t..., "\n"); }

//===================//
//  Added libraries  //
//===================//

//===================//
//end added libraries//
//===================//

void program();
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    program();
}


//===================//
//   begin program   //
//===================//

const int MX = 50000;

int n, m;
int SHUF[MX];
bool cw(int x, int y, int z) {
    return is_clockwise(SHUF[x],SHUF[y],SHUF[z]);
}
bool ccw(int x, int y, int z) {
    return !is_clockwise(SHUF[x],SHUF[y],SHUF[z]);
}
set<int> getOnSide(set<int>& pos, int x, int y, bool side) {
    set<int> ret;
    FOR(i,pos) {
        if(x == i || y == i) continue;
        if(cw(x,y,i) == side) ret.insert(i);
    }
    return ret;
}
int MEX(int x, int y) {
    RE1(i,3)
        if(x != i && y != i) return i;
}
int getBeg() {
    set<int> possible;
    RE1(i,n) possible.insert(i);
    int lst = -1;
    while(possible.sz >= 3) {
        int x = *possible.begin();
        int y = *++possible.begin();
        bool side = 0;
        if(lst != -1) side = cw(x,y,lst);
        possible = getOnSide(possible, x, y, side);
        if(possible.sz == 0) return x;
        lst = x;
    }
    return *possible.begin();
}

int origin;
int S[MX], C[MX];

void program() {
    n = get_n();
    RE1(i,n) SHUF[i] = i;
    shuffle(SHUF+1,SHUF+n+1,rng);
    if(n == 3) {
        give_answer(3);
        return;
    }
    origin = getBeg();
    RE(i,n) S[i] = i+1;
    RE(i,n) if(S[i] == origin) swap(S[i], S[0]);
    sort(S+1,S+n,[](int i, int j) {
        return ccw(origin, i, j);
    });

    m=0;
    C[m++] = S[n-1], C[m++] = S[0];
    int i=1;
    while(i < n) {
        if(ccw(C[m-2],C[m-1],S[i])) C[m++] = S[i++];
        else m--;
    }
    give_answer(m-1);
}

컴파일 시 표준 에러 (stderr) 메시지

tri.cpp: In function 'int MEX(int, int)':
tri.cpp:85:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

• Subtask 1: 0 / 15
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 20
• Subtask 5: 0 / 25