Submission #367867

#TimeUsernameProblemLanguageResultExecution timeMemory
367867nekiPlanine (COCI21_planine)C++14
0 / 110
8 ms1116 KiB
#include <bits/stdc++.h> #define ll long long #define loop(i, a, b) for(ll i=a;i<b;i++) #define pool(i, a, b) for(ll i=a-1;i>=b;i--) #define fore(i, a) for(auto&& i:a) #define fi first #define se second #define ps(a) push_back(a) #define pb(a) pop_back(a) #define sc scanf #define vc vector #define lb lower_bound #define ub upper_bound #define all(a) a.begin(), a.end() #define llmax LLONG_MAX/2 #define llmin -LLONG_MAX/2 using namespace std; #define mn 500100 #define par pair<ll, ll> #define ld long double #define mod 1000000007 ld eps=1e-9; ll vecpro(par s, par p1, par p2){ p1.fi-=s.fi; p2.fi-=s.fi; p1.se-=s.se; p2.se-=s.se; return p1.fi * p2.se - p2.fi * p1.se; } ld inter(par p1, par p2, ll h){ ld k=((ld)(p2.se - p1.se)) / (p2.fi - p1.fi); return ((ld)(h-p1.se + k * p1.fi))/k; } vc<ld> gt(vc<par> a, ll h ){ ll n=a.size(); vc<par> st; vc<ld> ret; for(ll i=1;i<n;i+=2){ while(st.size()>=2 and vecpro(st[st.size()-1], st[st.size()-2], a[i-1])<=0) st.pop_back(); st.ps(a[i-1]); while(st.size()>=2 and vecpro(st[st.size()-1], st[st.size()-2], a[i])<=0) st.pop_back(); ret.ps(inter(st.back(), a[i], h)-eps); //cout << st.back().fi<<" "<<st.back().se<<" "<<a[i].fi<<" "<<a[i].se <<" "<<inter(st.back(), a[i], h)<<endl; } return ret; } int main() { ll n, h;cin >> n>>h; vc<par> poi; loop(i, 0, n){ ll x, y;cin >> x >> y; if(i!=0 and i!=n-1)poi.ps(make_pair(x, y)); } vc<ld> a=gt(poi, h); reverse(all(poi)); fore(v, poi) v.fi=-v.fi; vc<ld> b=gt(poi, h); fore(v, b) v=-v; reverse(all(b)); n=a.size(); vc<pair<ld, ld>> ints; loop(i, 0, n) ints.ps(make_pair(a[i], b[i])); ints.ps(make_pair(llmax, llmax)); sort(all(ints)); //loop(i, 0, n) cout << ints[i].fi << " "<< ints[i].se<<endl; vc<ll> dp(n+1, 0); pool(i, n, 0){ ll odg=upper_bound(all(ints), make_pair((ld)ints[i].se, (ld)llmax))-ints.begin();//????????????????? dp[i]=1+dp[odg]; } cout << dp[0]<<endl; }
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