Submission #930591

#	Time	Username	Problem	Language	Result	Execution time	Memory
930591		guagua0407	Aliens (IOI16_aliens)	C++17	100 / 100	140 ms	9584 KiB

aliens

//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include "aliens.h"
using namespace std;
#define ll long long
#define pii pair<int,int>
#define f first
#define s second
#define all(x) x.begin(),x.end()
#define _ ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};

void setIO(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}
const int mxn=1e5+5;
const ll inf=1e18;
vector<ll> dp(mxn);
vector<int> cnt(mxn);
vector<ll> g(mxn);
vector<int> x,y;

struct line{
    ll a,b;
    ll val(ll x){
        return a*x+b;
    }
};

vector<line> L(mxn);

bool check(int a,int b,int c){
    line l1=L[a],l2=L[b],l3=L[c];
    if((__int128)(l3.b-l1.b)*(l1.a-l2.a)!=(__int128)(l2.b-l1.b)*(l1.a-l3.a)){
        return (__int128)(l3.b-l1.b)*(l1.a-l2.a)<=(__int128)(l2.b-l1.b)*(l1.a-l3.a);
    }
    return cnt[a]<=cnt[b];
}
ll c(int l,int r){
    ll a=(y[r]-x[l]+1);
    ll b=(l==1?0:max(0,y[l-1]-x[l]+1));
    return a*a-b*b;
}
// y[r]^2+x[l+1]^2+1+2y[r]-2x[l+1]-2x[l+1]y[r]
// y[i]^2+2y[r]+1+min(-2y[r]x[l+1]+x[l+1]^2-2x[l+1]+dp[l]-g[l+1])

int check(int n,ll cost){
    L[0]={-2*x[1],1ll*x[1]*x[1]-2*x[1]+cost};
    deque<int> vec;
    vec.push_back(0);
    for(int i=1;i<=n;i++){
        while((int)vec.size()>=2 and make_pair(L[vec[0]].val(y[i]),cnt[vec[0]])>=make_pair(L[vec[1]].val(y[i]),cnt[vec[1]])){
            vec.pop_front();
        }
        dp[i]=dp[vec[0]]+c(vec[0]+1,i)+cost;
        cnt[i]=cnt[vec[0]]+1;
        L[i]={-2*x[i+1],1ll*x[i+1]*x[i+1]-2*x[i+1]+dp[i]-g[i+1]+cost};
        while((int)vec.size()>=2 and check(vec[vec.size()-2],vec.back(),i)){
            vec.pop_back();
        }
        vec.push_back(i);
    }
    return cnt[n];
}

ll solve(int n,int m,int k){
    k=min(k,n);
    for(int i=2;i<=n;i++){
        g[i]=max(0,y[i-1]-x[i]+1);
        g[i]*=g[i];
    }
    ll l=0,r=(ll)1e12+1;
    while(l<r){
        ll mid=(l+r)/2;
        if(check(n,mid)<=k){
            r=mid;
        }
        else{
            l=mid+1;
        }
    }
    //cout<<l<<'\n';
    check(n,l);
    return dp[n]-k*l;
}

ll take_photos(int n, int m, int k, std::vector<int> r, std::vector<int> c){
    vector<pair<int,int>> vec(n);
    for(int i=0;i<n;i++){
        if(r[i]>c[i]) swap(r[i],c[i]);
        vec[i]={c[i],r[i]};
    }
    sort(all(vec));
    vector<pair<int,int>> st;
    for(int i=0;i<n;i++){
        while(!st.empty() and st.back().s>=vec[i].s){
            st.pop_back();
        }
        st.push_back(vec[i]);
    }
    x.push_back(-1);
    y.push_back(-1);
    for(auto v:st){
        x.push_back(v.s);
        y.push_back(v.f);
    }
    return solve(st.size(),m,k);
}

/*signed main(){
    int n,m,k;
    cin>>n>>m>>k;
    vector<int> r(n),c(n);
    for(int i=0;i<n;i++){
        cin>>r[i];
        cin>>c[i];
    }
    cout<<take_photos(n,m,k,r,c)<<'\n';
}*/
//maybe its multiset not set
//yeeorz
//laborz

Compilation message (stderr)

aliens.cpp: In function 'void setIO(std::string)':
aliens.cpp:16:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
aliens.cpp:17:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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