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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#109806 | #5570. Epidemic Escape | 2024zll | WA | 3ms | 4592kb | C++14 | 4.1kb | 2023-05-30 17:47:37 | 2023-05-30 17:47:40 |
Judging History
answer
#include<algorithm>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<queue>
#include<vector>
namespace IO{
const int ARR_SIZE=1<<20;
#define gc() ((IO::si!=IO::ti||(IO::ti=(IO::si=IO::input)+fread(IO::input,1,IO::ARR_SIZE,stdin))),IO::si!=IO::ti?*(IO::si++):EOF)
char input[ARR_SIZE],*si=input,*ti=input;
template<typename T>
void read(T&num){
bool flag=true;
int ch=gc();
num=0;
while(ch<48||ch>57){
if(ch=='-')flag=false;
ch=gc();
}
while(ch>=48&&ch<=57)num=num*10+(ch^48),ch=gc();
flag||(num=-num);
}
}
using IO::read;
typedef double real;
const int maxn=100000,maxk=5;
int n,q;
struct Vector{
real x,y;
Vector(const real x=0,const real y=0):x(x),y(y){}
friend bool operator<(const Vector&A,const Vector&B){
return A.x!=B.x?A.x<B.x:A.y<B.y;
}
friend Vector operator-(const Vector&A,const Vector&B){
return Vector(A.x-B.x,A.y-B.y);
}
friend Vector operator/(const Vector&A,const real&x){
return Vector(A.x/x,A.y/x);
}
friend real Cross(const Vector&A,const Vector&B){
return A.x*B.y-A.y*B.x;
}
friend real Dot(const Vector&A,const Vector&B){
return A.x*B.x+A.y*B.y;
}
}P[maxn],Q;
bool used[maxn];
std::vector<int>down[maxk],up[maxk],stack;
int B[maxk];
void PolygonToConvex(std::vector<int>&down,std::vector<int>&up,std::vector<int>&stack,int&k){
int end=n-1;
while(end>=0&&used[end])end--;
// printf("end = %d\n",end);
if(end==-1)return;
stack.resize(n*2);
int top=-1;
for(int i=0;i<=end;i++){
if(used[i])continue;
while(top>0&&Cross(P[stack[top]]-P[stack[top-1]],P[i]-P[stack[top]])<0)top--;
stack[++top]=i;
}
k=top;
for(int i=end-1;i>=0;i--){
if(used[i])continue;
while(top>k&&Cross(P[stack[top]]-P[stack[top-1]],P[i]-P[stack[top]])<0)top--;
stack[++top]=i;
}
stack.resize(top+1);
//printf("top = %d\n",top);
for(int i:stack)used[i]=true/*,printf("%d ",i)*/;
//printf("\n");//for debugging
down.assign(stack.begin(),stack.begin()+k+1);
if(k<top)up.assign(stack.begin()+k+1,stack.begin()+top+1);
}
int k;
struct CMP{
bool operator()(const int x,const int y)const{
return Dot(P[x],Q)>Dot(P[y],Q);
}
}cmp;
std::priority_queue<int,std::vector<int>,CMP>queue;
int vis[maxn],now_id;
void push(const int x){
// printf("push(x = %d)\n",x);
if(vis[x]==now_id)return;
vis[x]=now_id;
queue.push(x);
if((int)queue.size()>k)/*printf("pop: %d\n",queue.top()),*/queue.pop();
}
void solve(std::vector<int>&vec){
/*printf("vec:");
for(int i:vec)printf(" %d",i);
printf("\n");//for debugging*/
if((int)vec.size()<=k)
for(int i:vec)
push(i);
else{
for(int i=0;i<k;i++)push(vec[i]);
for(int i=(int)vec.size()-k;i<(int)vec.size();i++)push(vec[i]);
int l=0,r=vec.size()-2,mid;
while(l<r){
mid=(l+r)>>1;
if(Cross(Q-P[vec[mid]],P[vec[mid+1]]-P[vec[mid]])>0)r=mid;
else l=mid+1;
}
for(int i=std::max(0,l-k),lim=std::min((int)vec.size()-1,l+k);i<=lim;i++)push(vec[i]);
}
}
int main(){
read(n);
for(int i=0;i<n;i++)read(P[i].x),read(P[i].y),P[i]=P[i]/Dot(P[i],P[i]);
std::sort(P,P+n);
// for(int i=0;i<n;i++)printf("%lf %lf %d\n",P[i].x,P[i].y,i);
for(int i=0;i<maxk;i++)PolygonToConvex(down[i],up[i],stack,B[i]);
/*puts("up:");
for(int i=0;i<maxk;i++){
for(int j:up[i])printf("%d ",j);
putchar('\n');
}
puts("down:");
for(int i=0;i<maxk;i++){
for(int j:down[i])printf("%d ",j);
putchar('\n');
}*/
read(q);
memset(vis,-1,sizeof(int)*n);
for(int i=0,x,y;i<q;i++){
now_id=i;
// printf("- - - i = %d - - -\n",i);
read(x),read(y),read(k);
Q=Vector(x,y);
Q=Q/sqrt(Dot(Q,Q));
// printf("Q = (%lf, %lf)\n",Q.x,Q.y);
while(!queue.empty())queue.pop();
for(int j=0;j<k;j++)solve(down[j]);
for(int j=0;j<k;j++)solve(up[j]);
if((int)queue.size()<k){
puts("-1");
continue;
}
while((int)queue.size()>1)queue.pop();
const int u=queue.top();
// printf("u = %d\n",u);
const real dot=Dot(P[u],Q);
// printf("dot = %lf\n",dot);
if(dot==0)puts("-1");
else{
const real ans=(real)Dot(Q,Q)/dot/2;
if(ans<0)puts("-1");
else printf("%.10lf\n",ans);
}
}
return 0;
}
Details
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Test #1:
score: 100
Accepted
time: 2ms
memory: 4592kb
input:
5 5 -3 5 4 -6 2 -5 0 4 1 2 -3 -10 1 6 -9 1
output:
8.7002554241 3.2260195623
result:
ok 2 numbers
Test #2:
score: -100
Wrong Answer
time: 3ms
memory: 4536kb
input:
8 4 -1 4 -8 0 9 4 -7 -5 -2 5 -5 7 5 -9 2 10 4 -8 1 7 -7 5 -10 8 2 -9 9 2 4 -7 5 -1 -10 2 6 -3 2 2 -9 3 -10 -10 1 5 9 1
output:
3.1677629681 2.4041630560 5.1345807564 5.4640069455 2.9795300374 4.9488023892 2.1118419787 4.1907020260 2.9294423792 4.7617289402
result:
wrong answer 2nd numbers differ - expected: '26.1629509', found: '2.4041631', error = '0.9081081'