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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#498273 | #7906. Almost Convex | Susie_Rain | TL | 0ms | 4000kb | C++20 | 3.5kb | 2024-07-30 10:57:12 | 2024-07-30 10:57:13 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
//#define int long long
#define debug(x) cout<<x<<"--------------------------------------\n" ;
const int N = 1e5 + 10;
typedef long long ll;
const int INF = 1e9 ;
const int MOD = 1e9 + 7 ;
typedef pair<int,int> PII ;
int gcd(int a,int b){
return b ? gcd(b,a%b) : a ;
}
ll qpow(int a,int k){
ll res = 1 ;
while (k){
if(k&1) res = 1ll * res * a % MOD ;
a = 1ll * a * a % MOD ;
k >>= 1 ;
}
return res ;
}
int n;
#define double float
const double eps=1e-6;
const double PI=acos(-1);
inline int sgn(double x){
return fabs(x)<eps?0:(x<0?-1:1);
}
struct point{
double x,y;
point(double a=0,double b=0):x(a),y(b){}
point operator +(const point &A)const{
return point(x+A.x,y+A.y);
}
point operator -(const point &A)const{
return point(x-A.x,y-A.y);
}
point operator *(const double v)const{
return point(x*v,y*v);
}
point operator /(const double v)const{
return point(x/v,y/v);
}
bool operator ==(const point &A)const{
return sgn(x-A.x)==0&&sgn(y-A.y)==0;
}
bool operator <(const point &A)const{
if(fabs(x-A.x)<eps) return (x-A.x<-eps);
return x-A.x<-eps;
}
double norm(){
return sqrt(x*x+y*y);
}
};
double dot(point a,point b){ // |A||B|cosθ
return a.x*b.x+a.y*b.y;
}
double det(point a,point b){ // |A||B|sinΘ
return a.x*b.y-a.y*b.x;
}
using Point = point;
using Points = vector<Point>;
double theta(auto p) { return atan2(p.y, p.x); } // 求极角
bool lt(double a,double b){
return (a-b<-eps);
}
void psort(Points &ps, Point c = {}) // 极角排序
{
sort(ps.begin(), ps.end(), [&](auto p1, auto p2) {
return lt(theta(p1 - c), theta(p2 - c));
});
}
std::vector<point> getHull(std::vector<point> p) {
std::vector<point> h, l;
std::sort(p.begin(), p.end(), [&](auto a, auto b) {
if (a.x != b.x) {
return a.x < b.x;
} else {
return a.y < b.y;
}
});
p.erase(std::unique(p.begin(), p.end()), p.end());
if (p.size() <= 1) {
return p;
}
for (auto a : p) {
while (h.size() > 1 && det(a - h.back(), a - h[h.size() - 2]) <= 0) {
h.pop_back();
}
while (l.size() > 1 && det(a - l.back(), a - l[l.size() - 2]) >= 0) {
l.pop_back();
}
l.push_back(a);
h.push_back(a);
}
l.pop_back();
std::reverse(h.begin(), h.end());
h.pop_back();
l.insert(l.end(), h.begin(), h.end());
return l;
}
void solve(){
cin >> n;
Points a(n);
for(int i=0;i<n;i++) cin >> a[i].x >> a[i].y;
auto hull = getHull(a);
map<point,bool> mp;
for(auto x:hull) mp[x] = 1;
vector<point> now;
int ans = 1;
for(int i=0;i<n;i++){ // 枚举点
if(mp[a[i]]) continue;
now.clear(); point o = a[i];
// debug(1)
// cout << o.x << ' ' << o.y << '\n';
for(auto x:a){
if(x==o) continue;
now.push_back(x);
}
psort(now,o);
int m = (int)now.size();
for(int j=0;j<m;j++){
// cout << now[j].x << ' ' << now[j].y << '\n';
if(mp[now[j]]&&mp[now[(j+1)%m]]) ans ++;
}
}
cout << ans << '\n';
}
signed main(){
ios::sync_with_stdio(false) ;
cin.tie(0) ;
int tt = 1 ;
// cin >> tt ;
while (tt--) solve() ;
return 0 ;
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 0ms
memory: 4000kb
input:
7 1 4 4 0 2 3 3 1 3 5 0 0 2 4
output:
9
result:
ok 1 number(s): "9"
Test #2:
score: 0
Accepted
time: 0ms
memory: 3860kb
input:
5 4 0 0 0 2 1 3 3 3 1
output:
5
result:
ok 1 number(s): "5"
Test #3:
score: 0
Accepted
time: 0ms
memory: 3716kb
input:
3 0 0 3 0 0 3
output:
1
result:
ok 1 number(s): "1"
Test #4:
score: 0
Accepted
time: 0ms
memory: 3844kb
input:
6 0 0 3 0 3 2 0 2 1 1 2 1
output:
7
result:
ok 1 number(s): "7"
Test #5:
score: 0
Accepted
time: 0ms
memory: 3744kb
input:
4 0 0 0 3 3 0 3 3
output:
1
result:
ok 1 number(s): "1"
Test #6:
score: -100
Time Limit Exceeded
input:
2000 86166 617851 383354 -277127 844986 386868 -577988 453392 -341125 -386775 -543914 -210860 -429613 606701 -343534 893727 841399 339305 446761 -327040 -218558 -907983 787284 361823 950395 287044 -351577 -843823 -198755 138512 -306560 -483261 -487474 -857400 885637 -240518 -297576 603522 -748283 33...