Submission #749875

#	Time	Username	Problem	Language	Result	Execution time	Memory
749875		Desh03	Aliens (IOI16_aliens)	C++17	12 / 100	7 ms	340 KiB

aliens

#include "aliens.h"
#include <bits/stdc++.h>
using namespace std;

const long long INF = 1e18;

struct point {
    int x, y;
    bool operator < (const point &p) const {
        return x == p.x ? y < p.y : x < p.x;
    }
};

vector<point> r;
vector<long long> dp, ndp;

long long cost(int i, int j) {
    long long ext = (r[i].x <= r[i - 1].y ? (long long) (r[i - 1].y - r[i].x + 1) * (r[i - 1].y - r[i].x + 1) : 0);
    return (long long) (r[j].y - r[i].x + 1) * (r[j].y - r[i].x + 1) - ext;
}

void dnc(int i, int l, int r, int optl, int optr) {
    if (l > r) return;
    int mid = l + r >> 1, opt;
    long long w = INF;
    for (int k = optl; k <= min(mid, optr + 1); k++) {
        long long c = cost(k + 1, mid);
        if (w > dp[k] + c)
            w = dp[k] + c, opt = k;
    }
    ndp[mid] = w;
    dnc(i, l, mid - 1, optl, opt);
    dnc(i, mid + 1, r, opt, optr);
}

long long take_photos(int n, int m, int k, vector<int> R, vector<int> C) {
    vector<point> f;
    r = vector<point> ();
    for (int i = 0; i < n; i++) {
        if (R[i] > C[i]) swap(R[i], C[i]);
        f.push_back({R[i], C[i]});
    }
    sort(f.begin(), f.end());
    r.push_back(f[0]);
    for (int i = 1; i < n; i++) {
        if (r.back().x == f[i].x) {
            r.pop_back();
            r.push_back(f[i]);
        } else if (f[i].y > r.back().y) {
            r.push_back(f[i]);
        }
    }
    n = r.size();
    dp = vector<long long> (n), ndp = dp;
    for (int i = 0; i < n; i++) dp[i] = (long long) (r[i].y - r[0].x + 1) * (r[i].y - r[0].x + 1);
    long long ans = dp[n - 1];
    for (int i = 1; i < min(n, k); i++) dnc(i, i, n - 1, 0, n - 2), dp = ndp, ans = min(ans, dp[n - 1]);
    return ans;
}

Compilation message (stderr)

aliens.cpp: In function 'void dnc(int, int, int, int, int)':
aliens.cpp:24:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   24 |     int mid = l + r >> 1, opt;
      |               ~~^~~
aliens.cpp:32:8: warning: 'opt' may be used uninitialized in this function [-Wmaybe-uninitialized]
   32 |     dnc(i, l, mid - 1, optl, opt);
      |     ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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