Submission #272824

#	Time	Username	Problem	Language	Result	Execution time	Memory
272824		stoyan_malinin	Aliens (IOI16_aliens)	C++14	12 / 100	299 ms	4472 KiB

aliens

#include "aliens.h"
//#include "grader.cpp"

#include <cmath>
#include <vector>
#include <iostream>
#include <algorithm>

using namespace std;

const int MAXN = 505;

struct Point
{
    int r, c;

    Point(){}
    Point(int r, int c)
    {
        this->r = r;
        this->c = c;
    }
};

bool cmpCol(Point A, Point B)
{
    if(A.c!=B.c) return A.c<B.c;
    return A.r<B.r;
}

int n, m, k;
long long dp[MAXN][MAXN];

vector <Point> v;
int squareSz[MAXN][MAXN], leftestCover[MAXN][MAXN];

void init()
{
    for(int i = 0;i<n;i++)
    {
        for(int j = 0;j<=k;j++)
        {
            dp[i][j] = 6969696966969LL;
        }
    }

    for(int r = 0;r<v.size();r++)
    {
        int maxDist = -1;
        for(int l = r;l>=0;l--)
        {
            maxDist = max(maxDist, abs(v[l].c-v[l].r)+(v[r].c-v[l].c));
            squareSz[l][r] = maxDist + 1;
        }
    }

    for(int i = 0;i<n;i++)
    {

        for(int p = 0;p<=i;p++)
        {
            int d = squareSz[p][i];
            leftestCover[p][i] = i;

            for(int j = 0;j<p;j++)
            {
                if(v[i].c-v[j].c<d && abs(v[i].c-v[j].r)<d)
                {
                    leftestCover[p][i] = j;
                    break;
                }
            }
        }
    }

    //cout << "->" << leftestCover[1][4] << '\n';
}

long long squareNum(long long x)
{
    if(x<0) return 0;
    return x*x;
}

long long take_photos(int _n, int _m, int _k, vector<int> r, vector<int> c)
{
    n = _n;
    m = _m;
    k = _k;

    for(int i = 0;i<n;i++)
    {
        if(c[i]<r[i]) swap(c[i], r[i]);
    }

    for(int i = 0;i<n;i++) v.push_back(Point(r[i], c[i]));
    sort(v.begin(), v.end(), cmpCol);

    init();

    for(int i = 0;i<n;i++)
    {
       // cout << v[i].r << " --- " << v[i].c << '\n';
        //if(i!=n-1 && v[i].c==v[i+1].c) continue;

        dp[i][0] = squareNum(squareSz[0][i]);
        for(int j = 1;j<k;j++)
        {
            int cover = i;
            for(int p = i;p>=1;p--)
            {
                int side = squareSz[p][i];
                cover = min(cover, leftestCover[p][i]);

                //cout << p << " " << cover << '\n';
                if(cover>=p)
                {
                    dp[i][j] = min(dp[i][j],
                                   dp[p-1][j-1] + squareNum(squareSz[p][i])
                                   - squareNum(v[p-1].c-(v[i].c-squareSz[p][i])));
                }
            }
        }

        //cout << dp[i][0] << " " << dp[i][1] << '\n';
    }

    long long answer = 6996969969696996LL;
    for(int i = 0;i<k;i++) answer = min(answer, dp[n-1][i]);

    return answer;
}
/*
5 7 2
0 3
4 4
4 6
4 5
4 6

4 10 2
0 3
3 4
4 3
3 3
*/

Compilation message (stderr)

aliens.cpp: In function 'void init()':
aliens.cpp:47:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Point>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |     for(int r = 0;r<v.size();r++)
      |                   ~^~~~~~~~~
aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:112:21: warning: unused variable 'side' [-Wunused-variable]
  112 |                 int side = squareSz[p][i];
      |                     ^~~~

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