Submission #1017277

#	Time	Username	Problem	Language	Result	Execution time	Memory
1017277		khanhphucscratch	Aliens (IOI16_aliens)	C++14	Compilation error	0 ms	0 KiB

aliens

#include<bits/stdc++.h>
#include "aliens.h"
#define int long long
using namespace std;
struct CHT
{
    vector<pair<int, int>> line;
    vector<double> hull;
    double intersection(pair<int, int> x, pair<int, int> y)
    {
        return (double)(x.second - y.second) / (y.first - x.first);
    }
    void addline(pair<int, int> x)
    {
        while(hull.size() > 0 && intersection(x, line[line.size()-1]) <= hull[hull.size()-1]){
            hull.pop_back(); line.pop_back();
        }
        if(line.size() > 0) hull.push_back(intersection(line[line.size()-1], x));
        line.push_back(x);
    }
    int bestval(int x)
    {
        if(line.size() == 0) return 1e15;

        int place = lower_bound(hull.begin(), hull.end(), x) - hull.begin();
        return line[place].first*x+line[place].second;
    }
};
CHT st[1005];
int dp[1005][505], last[1005];
inline bool cmp(pair<int, int> x, pair<int, int> y)
{
    return x.second < y.second || (x.second == y.second && x.first > y.first);
}
int take_photos(int n, int m, int k, vector<int> r, vector<int> c)
{
    //Transform to segments
    vector<pair<int, int>> segment;
    for(int i = 0; i < n; i++){
        if(r[i] <= c[i]) segment.push_back({r[i], c[i]+1});
        else segment.push_back({c[i], r[i]+1});
    }
    //Eliminate unnecessary segments
    sort(segment.begin(), segment.end(), cmp);
    vector<pair<int, int>> sus;
    for(pair<int, int> i : segment){
        if(sus.size() > 0 && sus[sus.size()-1].first >= i.first && sus[sus.size()-1].second <= i.second){
            sus.pop_back();
        }
        sus.push_back(i);
    }
    memset(last, -1, sizeof(last));
    for(pair<int, int> i : sus){
        last[i.second] = i.first;
    }
    //O(mk log n) dp
    int lastplace = -1;
    st[0].addline({0, 0});
    for(int i = 0; i <= m; i++){
        for(int j = 0; j <= k; j++) if(last[i] > -1){
            pair<int, int> newline = make_pair(-2*last[i], last[i]*last[i]);
            if(lastplace > -1) newline.second += dp[lastplace][j];
            st[j].addline(newline);
        }
        for(int j = 0; j <= k; j++){
            if(last[i] == -1) dp[i][j] = dp[i-1][j];
            else{
                //cout<<st[0].bestval(i)<<endl;
                if(j > 0) dp[i][j] = i*i + st[j-1].bestval(i);
                else dp[i][j] = 1e15;
            }
            //cout<<i<<" "<<j<<" "<<dp[i][j]<<endl;
        }
        if(last[i] > -1) lastplace = i;
    }
    int ans = 1e18;
    for(int i = 0; i <= k; i++) ans = min(ans, dp[m][i]);
    return ans;
}
/*signed main()
{
    int x[2] = {1, 4}, y[2] = {4, 1};
    cout<<take_photos(2, 6, 2, x, y);
}*/

Compilation message (stderr)

/usr/bin/ld: /tmp/cc7QUZb6.o: in function `main':
grader.cpp:(.text.startup+0xf0): undefined reference to `take_photos(int, int, int, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >)'
collect2: error: ld returned 1 exit status