Submission #13850

#	Time	Username	Problem	Language	Result	Execution time	Memory
13850		gs14004	Wall construction (kriii2_WA)	C++14	1 / 4	0 ms	1244 KiB

WA

#include <cstdio>
#include <vector>
#include <algorithm>
#include <cmath>
using namespace std;
typedef pair<int,int> pi;

vector<pi> v;
pi a[1005];

bool ccw(pi a, pi b, pi c){
    int dx1 = b.first - a.first;
    int dy1 = b.second - a.second;
    int dx2 = c.first - a.first;
    int dy2 = c.second - a.second;
    if(dx1 * dy2 == dy1 * dx2) return 0;
    else return 2 * (dx1 * dy2 > dy1 * dx2) - 1;
}

bool cmp(pi p, pi q){
    int t = ccw(a[0],p,q);
    if(t == 1) return 1;
    else if(t == 0) return hypot(a[0].first - p.first,a[0].second - p.second) < hypot(a[0].first - q.first,a[0].second - q.second);
    return 0;
}

int n,r;

int main(){
    scanf("%d %d",&n,&r);
    for (int i=0; i<n; i++) {
        scanf("%d %d",&a[i].first,&a[i].second);
    }
    swap(a[0],*min_element(a,a+n));
    sort(a+1,a+n,cmp);
    int p = n-1;
    while (p > 0 && ccw(a[0],a[n-1],a[p-1]) == 0) {
        p--;
    }
    reverse(a+p,a+n);
    v.push_back(a[0]);
    for (int i=1; i<n; i++) {
        while (v.size() >= 2 && !ccw(v[v.size()-2],v.back(),a[i])) {
            v.pop_back();
        }
        v.push_back(a[i]);
    }
    double ret = 4 * asin(1) * r;
    for (int i=0; i<v.size(); i++) {
        ret += hypot(a[(i+1)%v.size()].first - a[i].first,a[(i+1)%v.size()].second - a[i].second);
    }
    printf("%.12lf",ret);
}

• Subtask 1: 1 / 1
• Subtask 2: 0 / 3