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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#578016 | #8082. Minimum Euclidean Distance | Auroraa | WA | 0ms | 3892kb | C++20 | 6.8kb | 2024-09-20 16:00:21 | 2024-09-20 16:00:22 |
Judging History
answer
#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
#define int long long
#define double long double
const int N=1e5+5;
const double pi=acos(-1);
const double eps=1e-8;
int sgn(double x){
if(fabs(x)<=eps)return 0;
return x<0?-1:1;
}
struct Point{
double x,y;
Point(){}
Point(double x,double y):x(x),y(y){}
Point operator+(const Point&a)const{return {x+a.x,y+a.y};}
Point operator-(const Point&a)const{return {x-a.x,y-a.y};}
double cross(const Point&a)const{return x*a.y-y*a.x;}
int toleft(const Point&a)const{return sgn(cross(a));}
double dot(const Point&a)const{return x*a.x+y*a.y;}
bool operator<(const Point&a)const{
if(x==a.x)return y<a.y;
return x<a.x;
}
bool operator==(const Point&a)const{return x==a.x && y==a.y;}
double dis2(const Point&a)const{return (x-a.x)*(x-a.x)+(y-a.y)*(y-a.y);}
double dis(const Point&a)const{return sqrt(dis2(a));}
double len()const{return sqrt(x*x+y*y);}
};
struct Segment{
Point a,b;
Segment(){}
Segment(Point a,Point b):a(a),b(b){}
bool operator<(const Segment&s)const{
return make_pair(a,b)< make_pair(s.a,s.b);
}
int is_on(const Point&p)const{
if(p==a || p==b)return -1;
return (p-a).toleft(p-b)==0 && (p-a).dot(p-b)<0;
}
double dis(const Point&p)const{
if(sgn((p-a).dot(b-a))==-1 || sgn((p-b).dot(a-b))==-1)return min(p.dis(a),p.dis(b));
Point p0=a,v=b-a;
return abs(v.cross(p-p0)/v.len());
}
};
struct Convex{
vector<Point>p;
// -1 在边上 | 0 在外部 | 1 在内部
int is_in(const Point&a)const{
if(p.size()==1)return a==p[0]?-1:0;
if(p.size()==2)
if(a==p[0])return -1;
if((p[1]-p[0]).toleft(a-p[0])==-1 || (p.back()-p[0]).toleft(a-p[0])==1)return 0;
auto cmp=[&](const Point&u,const Point&v){
return (u-p[0]).toleft(v-p[0])==1;
};
int pos=lower_bound(p.begin()+1,p.end(),a,cmp)-p.begin();
if(pos==1)return Segment(p[0],p[1]).is_on(a)?-1:0;
if(pos==p.size()-1 && Segment(p[0],p[pos]).is_on(a))return -1;
if(Segment(p[pos-1],p[pos]).is_on(a))return -1;
return (p[pos]-p[pos-1]).toleft(a-p[pos-1])>0;
}
// 返回切点下标
int find_max(const Point u){
int l=0,r=p.size()-1;
// x 的极角序小于 y
auto cmp=[&](const Point&x,const Point&y){
return (x-u).toleft(y-u)==1;
};
if(cmp(p[0],p.back())){ // 极值在 p[back]
while(l<r){
int mid=(l+r)>>1;
if(cmp(p[r],p[mid]) && cmp(p[mid+1],p[mid]))r=mid;
else l=mid+1;
}
}
else{ // 极值在 p[0]
while(l<r){
int mid=(l+r+1)>>1;
if(cmp(p[l],p[mid]) && cmp(p[mid-1],p[mid]))l=mid;
else r=mid-1;
}
}
return l;
}
int find_min(const Point u){
int l=0,r=p.size()-1;
// x 的极角序大于 y
auto cmp=[&](const Point&x,const Point&y){
return (y-u).toleft(x-u)==1;
};
if(cmp(p[0],p.back())){ // 极值在 p[back]
while(l<r){
int mid=(l+r)>>1;
if(cmp(p[r],p[mid]) && cmp(p[mid+1],p[mid]))r=mid;
else l=mid+1;
}
}
else{ // 极值在 p[0]
while(l<r){
int mid=(l+r+1)>>1;
if(cmp(p[l],p[mid]) && cmp(p[mid-1],p[mid]))l=mid;
else r=mid-1;
}
}
return l;
}
};
Convex Andrew(vector<Point>p){
vector<Point>st;
Convex ans;
sort(p.begin(), p.end());
auto check=[&](const vector<Point>&st,Point u){
Point tmp1=st.back(),tmp2=*prev(st.end(),2);
return (tmp1-tmp2).toleft(u-tmp1)<=0;
};
for(auto u:p){
while(st.size()>1 && check(st,u))st.pop_back();
st.push_back(u);
}
int k=st.size();
p.pop_back();
reverse(p.begin(), p.end());
for(auto u:p){
while(st.size()>k && check(st,u))st.pop_back();
st.push_back(u);
}
st.pop_back();
ans.p=st;
return ans;
}
void solve(){
int n,m;
cin>>n>>m;
vector<Point>vec;
for(int i=1;i<=n;i++){
int x,y;
cin>>x>>y;
vec.emplace_back(x,y);
}
// cin>>m;
Convex con=Andrew(vec);
vector<Point>p=con.p;
n=p.size();
double cir=0,area=0;
for(int i=0;i<n;i++){
cir+=p[i].dis(p[(i+1)%n]);
area+=p[i].cross(p[(i+1)%n]);
}
area/=2.0l;
while(m--){
int x1,y1,x2,y2;
cin>>x1>>y1>>x2>>y2;
Point a((x1+x2)/2.0l,(y1+y2)/2.0l);
double R=a.dis(Point(x1,y1));
double ans=R*R/2.0l;
if(con.is_in(a)){
cout<<fixed<<setprecision(10)<<ans<<endl;
continue;
}
auto nxt=[&](int x){return x==(n-1)?0:x+1;};
auto pre=[&](int x){return x==0?(n-1):x-1;};
int mx=con.find_max(a),mn=con.find_min(a);
double dis=min(Segment(p[mx],p[nxt(mx)]).dis(a),Segment(p[pre(mn)],p[mn]).dis(a));
int op1=sgn((p[nxt(mx)]-p[mx]).cross(a-p[mx])),op2=sgn((p[mn]-p[pre(mn)]).cross(a-p[pre(mn)]));
if(mx!=mn && op1 != op2){
int l=mx,r=mn-1;
if(r<l)r+=n;
while(l<r){
int mid=(l+r+1)>>1;
int p1=sgn((p[(mid+1)%n]-p[mid%n]).cross(a-p[mid%n]));
if(p1==op1)l=mid;
else r=mid-1;
}
l%=n;
dis=min(dis,Segment(p[l],p[nxt(l)]).dis(a));
}
ans+=dis*dis;
cout<<fixed<<setprecision(10)<<ans<<endl;
// int mx=con.find_max(a),mn=con.find_min(a);
// double dis=min(Segment(p[mx],p[nxt(mx)]).dis(a),Segment(p[pre(mn)],p[mn]).dis(a));
// int op1=sgn((p[nxt(mx)]-p[mx]).cross(a-p[mx])),op2=sgn((p[mn]-p[pre(mn)]).cross(a-p[pre(mn)]));
// if(mx!=mn && op1 != op2){
// int l=mx,r=mn-1;
// if(r<l)r+=n;
// while(l<r){
// int mid=(l+r+1)>>1;
// int p1=sgn((p[(mid+1)%n]-p[mid%n]).cross(a-p[mid%n]));
// if(p1==op1)l=mid;
// else r=mid-1;
// }
// l%=n;
// dis=min(dis,Segment(p[l],p[nxt(l)]).dis(a));
// }
// double s=cir*dis+pi*dis*dis+area;
// int t=0;
// while(s>area){
// t++;
// s/=2;
// }
// cout<<t<<endl;
}
}
signed main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int Te=1;
// cin>>Te;
while(Te--){
solve();
}
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 0ms
memory: 3892kb
input:
4 3 0 0 1 0 1 1 0 1 0 0 1 1 1 1 2 2 1 1 2 3
output:
0.2500000000 0.7500000000 1.8750000000
result:
ok Your answer is acceptable!^ ^
Test #2:
score: -100
Wrong Answer
time: 0ms
memory: 3864kb
input:
48 10 -30 0 -29 -4 -28 -7 -27 -9 -25 -12 -22 -16 -21 -17 -17 -20 -14 -22 -12 -23 -9 -24 -5 -25 -4 -25 0 -24 3 -23 5 -22 8 -20 12 -17 13 -16 16 -12 18 -9 19 -7 20 -4 21 0 21 1 20 5 19 8 18 10 16 13 13 17 12 18 8 21 5 23 3 24 0 25 -4 26 -5 26 -9 25 -12 24 -14 23 -17 21 -21 18 -22 17 -25 13 -27 10 -28 ...
output:
796.5000000000 235.0000000000 1051.2500000000 66.6250000000 426.3750000000 1211.8750000000 686.8750000000 521.8750000000 689.6250000000 436.2500000000
result:
wrong answer Except 589.500000000000, but found 796.500000000000!QAQ