Submission #562934

#	Time	Username	Problem	Language	Result	Execution time	Memory
562934		hoanghq2004	Aliens (IOI16_aliens)	C++17	100 / 100	203 ms	9624 KiB

aliens

#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include "aliens.h"

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;

const int N = 1e5 + 10;

struct Line {
    long long a, b;
    int t;
    long long operator() (long long x) {
        return a * x + b;
    }
};
vector <Line> convex;

int pointer;
int bad(const Line &L1, const Line &L2, const Line &L3) {
    return 1.0L * (L2.b - L1.b) * (L1.a - L3.a) >= 1.0L * (L3.b - L1.b) * (L1.a - L2.a);
}

void add(Line L) {
    while (convex.size() >= 2 && bad(convex.end()[-2], convex.back(), L)) convex.pop_back();
    convex.push_back(L);
    pointer = min(pointer, (int)convex.size() - 1);
}

pair <long long, int> get(long long x) {
    if (convex.empty()) return {1e18, 0};
    while (pointer < convex.size() - 1 && convex[pointer](x) > convex[pointer + 1](x)) ++pointer;
    return {convex[pointer](x), convex[pointer].t};
}
vector <pair <int, int> > P, Q;
pair <long long, int> f[N];

pair <long long, int> calc(long long C) {
    convex.clear(), pointer = 0;
    for (int i = 0; i < P.size(); ++i) {
        f[i] = {1LL * (P[i].second - P[0].first + 1) * (P[i].second - P[0].first + 1) + C, 1};
        pair <long long, int> cur = get(2 * (P[i].second + 1));
        cur.first += 1LL * (P[i].second + 1) * (P[i].second + 1) + C;
        ++cur.second;
        assert(f[i].first >= 0);
        f[i] = min(f[i], cur);
        if (i + 1 < P.size()) {
            long long delta = 0;
            if (P[i + 1].first <= P[i].second) {
                delta = 1LL * (P[i].second - P[i + 1].first + 1) * (P[i].second - P[i + 1].first + 1);
            }
            add({- P[i + 1].first, (1LL * P[i + 1].first * P[i + 1].first) - delta + f[i].first, f[i].second});
        }
    }
    return f[P.size() - 1];
}

long long take_photos(int n, int m, int k, std::vector<int> r, std::vector<int> c) {
    for (int i = 0; i < n; ++i) {
        if (r[i] > c[i]) swap(r[i], c[i]);
        P.push_back({r[i], - c[i]});
    }
    sort(P.begin(), P.end());
    for (auto &[x, y]: P) y = - y;
    for (auto [x, y]: P) {
        if (Q.size() && y <= Q.back().second) continue;
        Q.push_back({x, y});
    }
    swap(P, Q);
    if (calc(0).second <= k) return calc(0).first;
    long long L = 0, R = 1e13;
    while (L < R) {
        long long mid = L + R >> 1;
        if (calc(mid).second <= k) R = mid;
        else L = mid + 1;
    }
    return calc(L).first - L * k;
}

//int main() {
//    int n, m, k;
//    assert(3 == scanf("%d %d %d", &n, &m, &k));
//    std::vector<int> r(n), c(n);
//    for (int i = 0; i < n; i++) {
//        assert(2 == scanf("%d %d", &r[i], &c[i]));
//    }
//    long long ans = take_photos(n, m, k, r, c);
//
//
//    printf("%lld\n", ans);
//    return 0;
//}

Compilation message (stderr)

aliens.cpp: In function 'std::pair<long long int, int> get(long long int)':
aliens.cpp:38:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Line>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |     while (pointer < convex.size() - 1 && convex[pointer](x) > convex[pointer + 1](x)) ++pointer;
      |            ~~~~~~~~^~~~~~~~~~~~~~~~~~~
aliens.cpp: In function 'std::pair<long long int, int> calc(long long int)':
aliens.cpp:46:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |     for (int i = 0; i < P.size(); ++i) {
      |                     ~~^~~~~~~~~~
aliens.cpp:53:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   53 |         if (i + 1 < P.size()) {
      |             ~~~~~~^~~~~~~~~~
aliens.cpp: In function 'long long int take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:79:27: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   79 |         long long mid = L + R >> 1;
      |                         ~~^~~

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