Submission #975695

#	Time	Username	Problem	Language	Result	Execution time	Memory
975695		yeediot	Aliens (IOI16_aliens)	C++17	100 / 100	108 ms	4732 KiB

aliens

#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define pii pair<int,int>
#define pb push_back
#define sz(x) (int)(x.size())
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
#define vi vector<int>
#define vp vector<pii>
#define vvi vector<vi>
#define ykh mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count())
#define __lg(x) 63-__builtin_clzll(x)
#define pow2(x) (1LL<<x)
#define ll long long
#define tili tuple<int,ll,int>
const int mxn=1e5+5;
vector<pair<int,int>>p;
int n,m;
pair<ll,int> calc(tili f,int x){
    return {1LL*get<0>(f)*x+get<1>(f),get<2>(f)+1};
}
bool ck(tili l1,tili l2,tili l){
    auto [m1,b1,c1]=l1;
    auto [m2,b2,c2]=l2;
    auto [m,b,c]=l;
    //l1*l2<l2*l
    //(b1-b2)/(m2-m1)>(b1-b)/(m-m1)
    //(b1-b2)*(m-m1)>=(b1-b)*(m2-m1)
    return make_pair(1LL*(b1-b)*(m2-m1),c)<=make_pair(1LL*(b1-b2)*(m-m1),c2);
}
pair<ll,int> solve(ll cost){
    deque<tili>st;
    st.pb({-2*p[1].F,1LL*p[1].F*p[1].F,0});
    pair<ll,int>dp;
    for(int i=1;i<=n;i++){
        while(sz(st)>1 and calc(st[0],p[i].S)>=calc(st[1],p[i].S)){
            st.pop_front();
        }
        dp=calc(st.front(),p[i].S);
        dp.F+=1LL*p[i].S*p[i].S+cost;
        if(i==n)
            break;
        int d=max(0,p[i].S-p[i+1].F);
        tili l={-2*p[i+1].F,dp.F+1LL*p[i+1].F*p[i+1].F-1LL*d*d,dp.S};
        while(sz(st)>1 and ck(st.end()[-2],st.back(),l)){
            st.pop_back();
        }
        st.pb(l);
    }
    return dp;
}
bool cmp(pair<int,int>a,pair<int,int>b){
    return (a.F==b.F?a.S>b.S:a.F<b.F);
}
ll take_photos(int N,int M,int k,vector<int>R,vector<int>c){
    n=N;
    m=M;
    vector<pii>v;
    for(int i=0;i<n;i++){
        if(c[i]<R[i])swap(R[i],c[i]);
        v.pb({R[i],c[i]+1});
    }  
    sort(all(v),cmp);
    p.pb({-1,-1});
    for(int i=0;i<n;i++){
        if(p.empty() or v[i].S>p.back().S)p.pb(v[i]);
    }
    n=sz(p)-1;
    ll l=0,r=1LL*m*m;
    while(l<r){
        ll mm=l+r>>1;
        pair<ll,int> x=solve(mm);
        if(x.S>k){
            l=mm+1;
        }
        else{
            r=mm;
        }
    }
    return solve(l).F-1LL*l*k;
}

#ifdef local
signed main(){
    freopen("/Users/iantsai/Library/Mobile Documents/com~apple~CloudDocs/cpp/Empty.md","r",stdin);
    int n,m,k;
    cin>>n>>m>>k;
    vector<int> r(n),c(n);
    for(int i=0;i<n;i++){
        cin>>r[i]>>c[i];
    }
    cout<<take_photos(n,m,k,r,c)<<'\n';
}
#endif














 

Compilation message (stderr)

aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:74:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   74 |         ll mm=l+r>>1;
      |               ~^~

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 40 / 40