Submission #1206938

#	Time	Username	Problem	Language	Result	Execution time	Memory
1206938		_callmelucian	Circus (Balkan15_CIRCUS)	C++17	100 / 100	458 ms	12260 KiB

circus

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

using ll = long long;
using ld = long double;
using pl = pair<ll,ll>;
using pii = pair<int,int>;
using tpl = tuple<int,int,int>;

#define all(a) a.begin(), a.end()
#define filter(a) a.erase(unique(all(a)), a.end())

const int mn = 3e5 + 5;
int dp[mn], p[mn], n, m;
bool vis[mn];
vector<pii> sumOpt, difOpt;

int node (int layer, int i) { return layer * n + i; }

void dijkstra (int source) {
    priority_queue<pii> pq; pq.emplace(0, source);
    fill(dp, dp + 3 * n, INT_MAX), dp[source] = 0;

    function<void(int,int,int)> addTransition = [&] (int from, int to, int weight) {
        if (dp[from] + weight < dp[to]) {
            dp[to] = dp[from] + weight;
            pq.emplace(-dp[to], to);
        }
    };

    while (pq.size()) {
        int u = pq.top().second; pq.pop();
        if (vis[u]) continue;
        vis[u] = 1;
        int layer = u / n, idx = u % n;

        if (layer == 0) { /// real node
            // pass to suffix layer
            int sfx = lower_bound(p, p + n, dp[u] + p[idx]) - p;
            if (0 <= sfx && sfx < n)
                addTransition(u, node(1, sfx), p[sfx] - p[idx] - dp[u]);

            // pass to prefix layer
            int prf = upper_bound(p, p + n, p[idx] - dp[u]) - p - 1;
            if (0 <= prf && prf < n)
                addTransition(u, node(2, prf), p[idx] - p[prf] - dp[u]);
        }

        else if (layer == 1) { /// suffix node
            // pass to real layer
            addTransition(u, idx, 0);

            // pass to suffix layer
            if (idx + 1 < n)
                addTransition(u, node(1, idx + 1), p[idx + 1] - p[idx]);
        }

        else if (layer == 2) { /// prefix node
            // pass to real layer
            addTransition(u, idx, 0);

            // pass to prefix layer
            if (idx - 1 >= 0)
                addTransition(u, node(2, idx - 1), p[idx] - p[idx - 1]);
        }
    }
}

void init (int N, int M, int P[]) {
    /// input processing
    for (int i = 0; i < N; i++) p[i] = P[i];
    p[N] = M, n = N + 1, m = M;
    sort(p, p + n);

    /// run dijkstra
    int source = lower_bound(p, p + n, M) - p;
    dijkstra(node(0, source));

    /// preprocessing
    for (int i = 0; i < n; i++) {
        sumOpt.emplace_back(p[i] + dp[i], p[i]);
        difOpt.emplace_back(p[i] - dp[i], p[i]);
    }
    sort(all(sumOpt)), sort(all(difOpt));

    for (int i = 1; i < n; i++)
        sumOpt[i].second = max(sumOpt[i].second, sumOpt[i - 1].second);
    for (int i = n - 2; i >= 0; i--)
        difOpt[i].second = min(difOpt[i].second, difOpt[i + 1].second);
}

int minLength (int D) {
    int ans = INT_MAX;
    int toLeft = upper_bound(all(sumOpt), make_pair(D, INT_MAX)) - sumOpt.begin() - 1;
    int toRight = lower_bound(all(difOpt), make_pair(D, 0)) - difOpt.begin();
    if (0 <= toLeft && toLeft < n)
        ans = min(ans, D - sumOpt[toLeft].second);
    if (0 <= toRight && toRight < n)
        ans = min(ans, difOpt[toRight].second - D);
    return ans;
}

#ifdef LOCAL
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);

    int N = 3, M = 8;
    int P[3] = {0, 3, 6};

    init(N, M, P);
    cout << minLength(4) << " " << minLength(5) << "\n";

    return 0;
}
#endif // LOCAL

Compilation message (stderr)

grader.cpp: In function 'int main()':
grader.cpp:16:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |         scanf("%d%d", &N, &M);
      |         ~~~~~^~~~~~~~~~~~~~~~
grader.cpp:18:22: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |                 scanf("%d", &P[i]);
      |                 ~~~~~^~~~~~~~~~~~~
grader.cpp:21:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |         scanf("%d", &Q);
      |         ~~~~~^~~~~~~~~~
grader.cpp:23:22: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |                 scanf("%d", &d);
      |                 ~~~~~^~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 17 / 17
• Subtask 3: 23 / 23
• Subtask 4: 9 / 9
• Subtask 5: 31 / 31
• Subtask 6: 9 / 9