Submission #666176

#	Time	Username	Problem	Language	Result	Execution time	Memory
666176		ParsaS	Jakarta Skyscrapers (APIO15_skyscraper)	C++17	100 / 100	108 ms	6548 KiB

skyscraper

// In the name of God
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define mp make_pair
typedef long long ll;
const int N = 3e4 + 5;
int n, m;
int dis[N];
unordered_set<int> S[N];
bool vis[N];

void solve() {
    cin >> n >> m;
    int s = -1, t = -1;
    memset(dis, 63, sizeof dis);
    for (int i = 0; i < m; i++) {
        int b, p; cin >> b >> p;
        if (s != -1 && t == -1)
            t = b;
        if (s == -1)
            s = b;
        S[b].insert(p);
    }
    priority_queue<pair<int, int> > pq;
    pq.push(mp(0, s));
    dis[s] = 0;
    while (!pq.empty()) {
        int i = pq.top().se;
        pq.pop();
        if (vis[i])
            continue;
        vis[i] = true;
        int prv = -1;
        for (auto p : S[i]) {
            for (int j = i + p; j < n; j += p) {
                //cout << "check " << j << ' ' << dis[j] << '-' << dis[i] + (j - i) / p << endl;

                if (dis[j] > dis[i] + (j - i) / p) {
                    dis[j] = dis[i] + (j - i) / p;
                    pq.push(mp(-dis[j], j));
                }
                if (S[j].count(p))
                    break;
            }
            for (int j = i - p; j >= 0; j -= p) {
                //cout << "check " << j << ' ' << dis[j] << '-' << dis[i] + (i - j) / p << endl;
                if (dis[j] > dis[i] + (i - j) / p) {
                    dis[j] = dis[i] + (i - j) / p;
                    pq.push(mp(-dis[j], j));
                }
                if (S[j].count(p))
                    break;
            }
        }
    }
    cout << (dis[t] < 1e9 ? dis[t] : -1) << '\n';
}

int32_t main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    solve();

    return 0;
}

Compilation message (stderr)

skyscraper.cpp: In function 'void solve()':
skyscraper.cpp:36:13: warning: unused variable 'prv' [-Wunused-variable]
   36 |         int prv = -1;
      |             ^~~

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 14 / 14
• Subtask 4: 21 / 21
• Subtask 5: 43 / 43