Submission #705498

#	Time	Username	Problem	Language	Result	Execution time	Memory
705498		browntoad	SIR (COI15_sir)	C++14	100 / 100	179 ms	41736 KiB

sir

#include <bits/stdc++.h>
#pragma GCC optimize ("Ofast", "unroll-loops")
using namespace std;
#define ll long long
#define int ll
#define FOR(i,a,b) for (int i = (a); i<(b); i++)
#define REP(i,n) FOR(i,0,n)
#define REP1(i,n) FOR(i,1,n+1)
#define RREP(i,n) for (int i=(n)-1; i>=0; i--)
#define f first
#define s second
#define pb push_back
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)(x.size())
#define SQ(x) (x)*(x)
#define pii pair<int, int>
#define pdd pair<double ,double>
#define pcc pair<char, char> 
#define endl '\n'
//#define TOAD
#ifdef TOAD
#define bug(x) cerr<<__LINE__<<": "<<#x<<" is "<<x<<endl
#define IOS()
#else
#define bug(...)
#define IOS() ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#endif

const ll inf = 1ll<<60;
const int iinf=2147483647;
const ll mod = 1e9+7;
const ll maxn=1e5+5;
const double PI=acos(-1);

ll pw(ll x, ll p, ll m=mod){
    ll ret=1;
    while (p>0){
        if (p&1){
            ret*=x;
            ret%=m;
        }
        x*=x;
        x%=m;
        p>>=1;
    }
    return ret;
}

ll inv(ll a, ll m=mod){
    return pw(a,m-2);
}

//=======================================================================================

struct Point{
	int x, y;
	int operator *(Point b){
		return x*b.y-y*b.x;
	}
	Point operator -(Point b){
		return {x-b.x, y-b.y};
	}
};
bool cmp(Point a, Point b){
    if (a.x == b.x) return a.y<b.y;
    return a.x<b.x;
}
int n, m;
int cid, pid;
vector<Point> C, P; // cheese and pepper 
int area(Point a, Point b, Point c){
	return abs((b-a)*(c-a));
}
vector<Point> low_hull(vector<Point> a){
    // assume alr sorted
    vector<Point> tmp;
    REP(i, SZ(a)){
        while(SZ(tmp)>=2 && ((a[i]-tmp[SZ(tmp)-1])*(tmp[SZ(tmp)-2]-tmp[SZ(tmp)-1])) < 0){
            tmp.pop_back();
        }
        tmp.pb(a[i]);
    }
    tmp.pop_back();
    return tmp;
}
vector<Point> convex_hull(vector<Point> a){
    sort(ALL(a), cmp);
    if (SZ(a) == 1) return a;
    vector<Point> hull = low_hull(a);
    reverse(ALL(a));
    vector<Point> tmp = low_hull(a);
    REP(i, SZ(tmp)) hull.pb(tmp[i]);
    return hull;
}
signed main (){
    IOS();
    cin>>n;
    REP(i, n){
    	int x, y; cin>>x>>y;
    	C.pb({x, y});
    }
    int m; cin>>m;
    REP(i, m){
    	int x, y; cin>>x>>y;
    	P.pb({x, y});
    }
    P=convex_hull(P);
    m=SZ(P);
    cid = 1; pid=0;
    REP(j, m){
        if (((P[j]-C[0])*(P[pid]-C[0])) > 0) pid = j;
    }
    int carea = 0, res = 0;
    REP(i, n){
    	while(((P[(pid+1)%m]-C[i])*(P[pid]-C[i])) > 0) {
    		pid = (pid+1)%m;
    	}
    	while(cid!=i && ((C[cid]-C[i])*(P[pid]-C[i])) > 0){
    		carea += area(C[i], C[(cid-1+n)%n], C[cid]);
    		cid = (cid+1)%n;
    	}
    	res = max(res, carea);
    	carea -= area(C[(cid-1+n)%n], C[i], C[(i+1)%n]);
    }
    cout<<res<<endl;
}
/*
0:24
*/

• Subtask 1: 12 / 12
• Subtask 2: 39 / 39
• Subtask 3: 49 / 49