#include <bits/stdc++.h>
using namespace std;
#define sf scanf
#define pf printf
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()
#define INF 1023456789
typedef long long ll;
typedef long double ld;
typedef pair<ld,ld> ii;
int n,h,x[1000005],y[1000005];
struct line{
ll x1,x2,y1,y2;
int cross(line &o){//where does this line intersect
ll x3=o.x1,x4=o.x2,y3=o.y1,y4=o.y2;
if((x1-x2)*(y3-y4)==(x3-x4)*(y1-y2))return 2;//parallel
ll num=(y3-y4)*(y1*(y1-y2)-x1*(x1-x2))-(y1-y2)*(y3*(y3-y4)-x3*(x3-x4));
ll den=(y1-y2)*(x3-x4)-(y3-y4)*(x1-x2);
if(num==h*den)return 0;//intersect exactly
if((den>0&&num<h*den)||(den<0&&num>h*den))return 1;//intersect above
if((den>0&&num>h*den)||(den<0&&num<h*den))return -1;//intersect below
}
bool cmp(line &o){
if(x1<o.x1){
if(cross(o)<=0)return false;
else return true;
}
else{
if(cross(o)==-1)return true;
else return false;
}
}
void print(){
pf("{%lld %lld %lld %lld} ",x1,y1,x2,y2);
}
};
struct valley{
int i;
line l1,l2;
void print(){
pf("%d: ",i);
l1.print();
l2.print();
pf("\n");
}
};
vector<valley> r;
int main(){
sf("%d%d",&n,&h);
for(int i=1;i<=n;++i)sf("%d%d",&x[i],&y[i]);
for(int i=3;i<n;i+=2){
line l1={x[i],x[i-1],y[i],y[i-1]};
line l2={x[i],x[i+1],y[i],y[i+1]};
r.pb({i,l1,l2});
}
sort(all(r),[](valley &a,valley &b){
return a.l2.cmp(b.l2);
});
/*
for(valley &i:r)i.print();
for(int i=0;i<3;++i){
for(int j=0;j<3;++j)pf("%d ",r[i].l2.cross(r[j].l2));
pf("\n");
}
for(int i=0;i<3;++i){
for(int j=0;j<3;++j)pf("%d ",r[i].l2.cmp(r[j].l2));
pf("\n");
}
*/
int ans=0;
line pv=r[0].l1;
pv.x1-=1;pv.x2-=1;
for(int i=0;i<sz(r);++i){
if(pv.cmp(r[i].l1)==1){
++ans;pv=r[i].l2;
}
}
pf("%d\n",ans);
}
Compilation message
Main.cpp: In function 'int main()':
Main.cpp:58:4: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
58 | sf("%d%d",&n,&h);
| ^
Main.cpp:59:25: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
59 | for(int i=1;i<=n;++i)sf("%d%d",&x[i],&y[i]);
| ^
Main.cpp: In member function 'int line::cross(line&)':
Main.cpp:28:2: warning: control reaches end of non-void function [-Wreturn-type]
28 | }
| ^
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
4 ms |
1072 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
1 ms |
468 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
4 ms |
1072 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
