Submission #812937

#	Time	Username	Problem	Language	Result	Execution time	Memory
812937		FatihSolak	Aliens (IOI16_aliens)	C++17	100 / 100	141 ms	8776 KiB

aliens

#include "aliens.h"
#include <bits/stdc++.h>
using namespace std;
struct CHT{
    deque<pair<long long,int>> lines;
    deque<long long> times;
    deque<int> cnt;
    long long intersect(pair<long long,int> line1, pair<long long,int> line2){
        return (line2.first - line1.first + (line1.second - line2.second)) / (line1.second - line2.second);
    }
    void add_line(pair<long long,int> line,int num){
        long long opt = 0;
        while(lines.size()){
            opt = max(opt,intersect(lines.back(),line));
            if(opt <= times.back()){
                lines.pop_back();
                times.pop_back();
                cnt.pop_back();
            }
            else break;
        }
        lines.push_back(line);
        times.push_back(opt);
        cnt.push_back(num);
    }
    pair<long long,int> get(int x){
        while(times.size() > 1 && times[1] <= x){
            times.pop_front();
            lines.pop_front();
            cnt.pop_front();
        }
        return {lines[0].first + (long long) x * lines[0].second,cnt[0]};
    }
};
long long take_photos(int n, int m, int k, vector<int> r, vector<int> c){
    vector<pair<long long,long long>> points;
    for(int i = 0;i<n;i++){
        if(r[i] < c[i])
            swap(r[i],c[i]);
        points.push_back({r[i],c[i]});
    }
    sort(points.begin(),points.end(),[&](pair<int,int> a,pair<int,int> b){
        if(a.first == b.first)
            return a.second > b.second;
        return a.first < b.first;
    });
    vector<pair<long long,long long>> tmp;
    for(auto u:points){
        while(tmp.size() && tmp.back().second >= u.second){
            tmp.pop_back();
        }
        tmp.push_back(u);
    }
    points = tmp;
    // for(auto u:points){
    //     cerr << u.first << ' ' << u.second << endl;
    // }
    n = points.size();
    function<pair<int,long long>(long long)> get = [&](long long C){
        // cout << C << endl;
        CHT vals;
        vector<long long> dp(n+1);
        vector<int> cnt(n+1);
        for(int i = 1;i<=n;i++){
            long long val = dp[i-1] + points[i-1].second * points[i-1].second - 2*points[i-1].second;
            if(i > 1)
                val -= max(0ll,points[i-2].first - points[i-1].second + 1) *  max(0ll,points[i-2].first - points[i-1].second + 1);
            
            vals.add_line({val,-2*points[i-1].second},cnt[i-1]);
            auto x = vals.get(points[i-1].first);
            dp[i] = x.first + points[i-1].first * points[i-1].first + 2 * points[i-1].first + 1 + C;
            cnt[i] = x.second + 1;
            // long long tmp = dp[i];
            // dp[i] = 2e18;
            // for(int j = 0;j<i;j++){
            //     long long extra = 0;
            //     if(j > 0)
            //         extra -= max(0ll,points[j-1].first - points[j].second + 1) *  max(0ll,points[j-1].first - points[j].second + 1);
            //     // cout << j << ' ' << extra << endl;
            //     long long num = dp[j] + (points[i-1].first - points[j].second  + 1) * (points[i-1].first - points[j].second  + 1)  + extra + C;
            //     if(num < dp[i]){
            //         dp[i] = num;
            //         cnt[i] = cnt[j] + 1; 
            //     }
            // }
            // assert(tmp == dp[i]);
        } 
        return make_pair(cnt[n],dp[n] - k * C);
    };
    long long tl = 0,tr = (long long)m * m;
    while(tl < tr){
        long long tm = (tl + tr)/2;
        if(get(tm).first <= k){
            tr = tm;
        }
        else tl = tm + 1;
    }
    return get(tl).second;
}

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