Submission #241499

#	Time	Username	Problem	Language	Result	Execution time	Memory
241499		osaaateiasavtnl	Railway Trip (JOI17_railway_trip)	C++17	0 / 100	10 ms	8320 KiB

railway_trip

#include<bits/stdc++.h>
using namespace std;
#define ii pair <int, int>
#define app push_back
#define all(a) a.begin(), a.end()
#define bp __builtin_popcountll
#define ll long long
#define mp make_pair
#define f first
#define s second
#define Time (double)clock()/CLOCKS_PER_SEC
 
const int N = 2007;
int n, k, q;
int a[N];
 
vector <int> g[N];
 
void bfs(int S, int dist[N]) {
    queue <int> q;
    for (int i = 0; i < N; ++i)
        dist[i] = N;
    q.push(S);
    dist[S] = 0;
    while (q.size()) {
        int u = q.front(); q.pop();
        for (int v : g[u]) {
            if (dist[u] + 1 < dist[v]) {
                dist[v] = dist[u] + 1;
                q.push(v);
            }   
        }   
    }   
}
 
int dist[N][N];
 
signed main() {
    #ifdef HOME
    freopen("input.txt", "r", stdin);
    #else
    #define endl '\n'
    ios_base::sync_with_stdio(0); cin.tie(0);
    #endif
    cin >> n >> k >> q;
 
    if (n >= N)
        exit(1);
 
    for (int i = 1; i <= n; ++i)
        cin >> a[i];
 
    set <ii> p;

    for (int i = 1; i <= n; ++i) {
        int cur = -1;
        int l = -1, r = -1;
        for (int j = i - 1; j >= 0; --j) {
            if (a[j] >= a[i]) {
                l = j;
                break;
            }
        }   
        cur = -1;
        for (int j = i + 1; j <= n; ++j) {
            if (a[j] >= a[i]) {
                r = j;
                break;
            }                        
        }   

        if (l != -1) {
            p.insert(mp(l, i));
            if (r == -1 || a[l] >= a[r]) {
                g[i].app(l);
            }   
        }

        if (r != -1) {
            p.insert(mp(i, r));
            if (l == -1 || a[r] >= a[l]) {
                g[i].app(r);
            }   
        }   
    }   
 
    for (int i = 1; i <= n; ++i) {
        bfs(i, dist[i]);
    }            
 
    while (q--) {
        int i, j;
        cin >> i >> j;
 
        if (j < i)
            swap(i, j);

        if (p.find(mp(i, j)) != p.end()) {
            cout << 0 << endl;
            continue;
        }   

        int ans = N;
        for (int k = 1; k <= n; ++k) {
            ans = min(ans, dist[i][k] + dist[j][k]);
        }   
        cout << ans - 1 << endl;
    }   
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 15
• Subtask 3: 0 / 25
• Subtask 4: 0 / 55