Submission #37935

#	Time	Username	Problem	Language	Result	Execution time	Memory
37935		patrikpavic2	SIR (COI15_sir)	C++14	0 / 100	309 ms	18404 KiB

sir

#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <cmath>

#define mp make_pair
#define X first
#define Y second

using namespace std;

typedef long long llint;
typedef pair < llint,llint> pii;

const llint N = 1e5 + 500;
const llint INF = 0x3f3f3f3f;
const llint MOD = 1e9 + 7;
vector < pii > hull;
vector < pii > v2;
vector < pii > hull2;
pii P;
llint n,m,nn;

llint ccw(pii A,pii B,pii C){
    return A.X * (B.Y - C.Y) + B.X * (C.Y - A.Y) + C.X * (A.Y - B.Y);
}

llint dis(pii A,pii B){
    return (A.X - B.X) * (A.X - B.X) + (A.Y - B.Y) * (A.Y - B.Y);
}

bool cmp(pii A,pii B){
    if(ccw(A,B,P) == 0) return dis(A,P) < dis(B,P);
    return ccw(P,A,B) > 0;
}

void convex_hull(){
    if(v2.size() < 3) {hull2 = v2;return;}
    int j = 0;
    for(int i = 0;i<v2.size();i++){
        if(v2[i].Y < v2[j].Y || (v2[i].Y == v2[i].Y && v2[i].X > v2[i].X))
            j = i;
    }
    swap(v2[0],v2[j]);
    P = v2[0];
    sort(v2.begin() + 1,v2.end(),cmp);
    hull2.push_back(P);
    hull2.push_back(v2[1]);
    hull2.push_back(v2[2]);
    nn = 3;
    for(int i = 3;i<m;i++){
        while(nn >= 3 && ccw(hull2[nn-2],hull2[nn-1],v2[i]) < 0){
            hull2.pop_back();
            nn = hull2.size();
        }
        hull2.push_back(v2[i]);
        nn = hull2.size();
    }
}

llint solve(){
    llint sol = 0;
    llint cur = 0;
    int j = 0,k = 0;
    for(int i = 0;i<n;i++){
        while(nn > 1 && ccw(hull[i],hull2[k],hull2[(k+1)%nn]) <= 0){
            k=(k+1)%nn;
        }
        if(i == j)
            j = (j + 1) % n;
        while(ccw(hull[i],hull[j],hull2[k]) > 0){
            cur += abs(ccw(hull[i],hull[(j-1+n)%n],hull[j]));
            j=(j+1)%n;
        }
        sol = max(sol, cur);
        if(i != j && i + 1 != j)
            cur -= abs(ccw(hull[i],hull[(i+1)%n],hull[(j-1+n)%n]));
        if(i == j)
            j = (j + 1) % n;
    }
    return sol;
}

void load(){
    scanf("%lld",&n);
    for(llint i = 0;i<n;i++){
        llint x,y;scanf("%lld%lld",&x,&y);
        hull.push_back(make_pair(x,y));
    }
    scanf("%lld",&m);
    for(llint i = 0;i<m;i++){
        llint x,y;scanf("%lld%lld",&x,&y);
        v2.push_back(make_pair(x,y));
    }
}

int main(){
    load();
    convex_hull();
    printf("%lld\n",solve());
}

Compilation message (stderr)

sir.cpp: In function 'void convex_hull()':
sir.cpp:43:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0;i<v2.size();i++){
                    ^
sir.cpp: In function 'void load()':
sir.cpp:88:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld",&n);
                     ^
sir.cpp:90:42: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         llint x,y;scanf("%lld%lld",&x,&y);
                                          ^
sir.cpp:93:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld",&m);
                     ^
sir.cpp:95:42: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         llint x,y;scanf("%lld%lld",&x,&y);
                                          ^

• Subtask 1: 0 / 12
• Subtask 2: 0 / 39
• Subtask 3: 0 / 49