Submission #225852

#	Time	Username	Problem	Language	Result	Execution time	Memory
225852		VEGAnn	Aliens (IOI16_aliens)	C++14	60 / 100	317 ms	95600 KiB

aliens

#include <bits/stdc++.h>
#include "aliens.h"
#define sz(x) ((int)x.size())
#define pii pair<int, int>
#define MP make_pair
#define PB push_back
#define ft first
#define sd second
#define all(x) x.begin(),x.end()
using namespace std;
typedef long long ll;
const int N = 50100;
const int K = 110;
const ll OO = 1e18;
vector<pii> vc, seg;
int n, m, k;
ll f[N][K], val[N];

ll sqr(ll x) { return x * x; }

struct line{
    ll k, b;

    line(): k(0), b(0) {}

    line(ll _b, ll _k): k(_k), b(_b) {}
};

vector<line> cht;

ll get_cross_point(line a, line b){
    ll K = a.k - b.k;
    ll B = b.b - a.b;

    if ((B <= 0 && K < 0) || (B >= 0 && K > 0))
        return B / K + bool((B % K) != 0);
    else return B / K;
}

void insert_to_cht(line nw){
    while (sz(cht) > 1){
        ll fi = get_cross_point(nw, cht.back());
        ll se = get_cross_point(cht.back(), cht[sz(cht) - 2]);

        if (se < fi) break;

        cht.pop_back();
    }

    cht.PB(nw);
}

long long take_photos(int N, int M, int K, std::vector<int> r, std::vector<int> c) {
    n = N; m = M; k = K;

    for (int i = 0; i < n; i++)
        vc.PB(MP(min(r[i], c[i]), -max(r[i], c[i])));

    sort(all(vc));

    int lst = -vc[0].sd;

    seg.PB(vc[0]);
    seg.back().sd *= -1;
    seg.back().ft--;

    for (int i = 1; i < sz(vc); i++){
        pii cr = vc[i];

        if (-cr.sd <= lst) continue;

        lst = -cr.sd;

        seg.PB(cr);
        seg.back().sd *= -1;
        seg.back().ft--;
    }

    n = sz(seg);
    k = min(n, k);

    for (int j = 1; j <= n; j++)
        if (seg[j - 1].sd > seg[j].ft)
            val[j] = -sqr(seg[j - 1].sd - seg[j].ft);

    for (int i = 0; i <= n; i++)
        for (int j = 0; j <= k; j++)
            f[i][j] = OO;

    f[0][0] = 0;

    for (int kl = 1; kl <= k; kl++) {
        cht.clear();

        cht.PB({f[0][kl - 1] + sqr(seg[0].ft), -2 * ll(seg[0].ft)});

        int ptr = 0;

        for (int i = 1; i <= n; i++){
            ptr = min(ptr, sz(cht) - 1);

            while (ptr + 1 < sz(cht) && get_cross_point(cht[ptr], cht[ptr + 1]) <= ll(seg[i - 1].sd))
                ptr++;

            ll nw = cht[ptr].b + cht[ptr].k * ll(seg[i - 1].sd) + sqr(seg[i - 1].sd);

            f[i][kl] = min(f[i][kl], nw);

            if (i < n)
                insert_to_cht({f[i][kl - 1] + val[i] + sqr(seg[i].ft), -2 * ll(seg[i].ft)});
        }
    }

    return f[n][k];
}

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