Submission #1131408

#	Time	Username	Problem	Language	Result	Execution time	Memory
1131408		Luvidi	Aliens (IOI16_aliens)	C++20	60 / 100	1933 ms	1114112 KiB

aliens

#include <bits/stdc++.h>
#include "aliens.h"
using namespace std;

struct Line{
    long long m,c;
    Line(long long M,long long C){
        m=M;
        c=C;
    }
    long long get(long long x){
        return m*x+c;
    }
    double inter(Line l2){
        double x=l2.c-c,y=m-l2.m;
        return x/y;
    }
};
 
vector<Line> ch;
 
bool cmp(Line x,Line y,Line z){
    return x.inter(y)<y.inter(z);
}
 
void add(Line x){
    while(ch.size()>1&&!cmp(ch[ch.size()-2],ch.back(),x))ch.pop_back();
    ch.push_back(x);
}

long long take_photos(int n, int m, int k, std::vector<int> r, std::vector<int> c) {
    vector<pair<int,int>> tm,st;
    for(int i=0;i<n;i++){
        if(r[i]>c[i])swap(r[i],c[i]);
        tm.push_back({r[i],c[i]});
    }
    sort(tm.begin(),tm.end(),[](pair<int,int> p1,pair<int,int> p2){
        if(p1.first!=p2.first)return p1.first<p2.first;
        return p1.second>p2.second;
    });
    st.push_back({-1,-1});
    for(auto p:tm){
        if(p.second>st.back().second)st.push_back(p);
    }
    n=st.size()-1;
    long long dp[n+1][k+1],a[n+1],h[n+1];
    for(int i=0;i<=n;i++){
        a[i]=st[i].second+1;
        h[i]=st[i].second-st[i].first+1;
    }
    for(int i=1;i<=n;i++)dp[i][0]=1e18;
    for(int i=0;i<=k;i++)dp[0][i]=0;
    for(int j=1;j<=k;j++){
        ch.clear();
        int idx=0;
        for(int i=1;i<=n;i++){
            long long x=-a[i]+h[i],y=max(0LL,a[i-1]-a[i]+h[i]),m=2*x,c=dp[i-1][j-1]-y*y+x*x;
            add(Line(m,c));
            idx=min(idx,(int)ch.size()-1);
            while(idx+1<ch.size()&&ch[idx].inter(ch[idx+1])<a[i])idx++;
            dp[i][j]=ch[idx].get(a[i])+a[i]*a[i];
        }
    }
    return dp[n][k];
}

Compilation message (stderr)

aliens.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~
aliens_c.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 0 / 40