Submission #274795

#	Time	Username	Problem	Language	Result	Execution time	Memory
274795		stoyan_malinin	Aliens (IOI16_aliens)	C++14	60 / 100	930 ms	190892 KiB

aliens

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

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

using namespace std;

const int MAXN = 5e4 + 5;

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;

vector <int> opt[MAXN];
vector <long long> dp[MAXN];

vector <Point> v;
void init()
{
    for(int i = 0;i<n;i++)
    {
        opt[i].assign(k+5, 0);
        dp[i].assign(k+5, 69696969969699LL);
    }

    vector <Point> newV;
    for(Point p: v)
    {
        int d = p.c - p.r + 1;
        while(newV.empty()==false && p.c-newV.back().c<d && abs(p.c-newV.back().r)<d) newV.pop_back();

        newV.push_back(p);
    }

    v = newV;
    n = v.size();
}

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

int getSquareSz(int l, int r)
{
    return (v[l].c-v[l].r) + (v[r].c-v[l].c) + 1;
}

void evalState(int mid, int lOpt, int rOpt, int j)
{
    rOpt = min(rOpt, mid);
    for(int p = lOpt;p<=rOpt;p++)
    {
        long long curr;
        if(p!=0) curr = dp[p-1][j-1] + squareNum(getSquareSz(p, mid))
                        - squareNum(v[p-1].c-(v[mid].c-getSquareSz(p, mid)));
        else
            curr = squareNum(getSquareSz(p, mid));

        if(dp[mid][j]>curr)
        {
            opt[mid][j] = p;
            dp[mid][j] = curr;
        }
        //cout << p << " -> " << squareNum(v[p-1].c-(v[i].c-squareSz[p][i])) << " " << side << '\n';
    }
}

void evalDP(int l, int r, int lOpt, int rOpt, int j)
{
    if(l>r) return;

    int mid = (l+r)/2;
    evalState(mid, lOpt, rOpt, j);

    evalDP(l, mid-1, lOpt, opt[mid][j], j);
    evalDP(mid+1, r, opt[mid][j], rOpt, j);
}

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++) dp[i][0] = squareNum(getSquareSz(0, i));

    if(k<=105)
    {
        for(int j = 1;j<k;j++)
        {
            evalDP(0, n-1, 0, n-1, j);
        }
    }
    else
    {
        for(int j = 1;j<k;j++)
        {
            for(int i = n-1;i>=0;i--)
            {
                int lOpt = ((j==1)?0:opt[i][j-1]);
                int rOpt = ((i==n-1)?i:opt[i+1][j]);
                evalState(i, lOpt, rOpt, j);
            }
        }
    }

    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

5 10 2
0 3
3 4
4 3
3 3
4 2
*/

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