Distinct Routes

#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;

const int MAXN = 501;
vector<int> adj[MAXN];   // Adjacency list to store the teleporters
vector<int> visited(MAXN, 0);  // Visited array to track visited rooms
vector<int> parent(MAXN, -1);  // To store the parent of each node in the path
vector<vector<int>> routes;    // To store all valid routes

// BFS to find the shortest path from room 1 to room n
bool bfs(int n) {
    queue<int> q;
    q.push(1);
    visited.assign(MAXN, 0);   // Reset visited array
    parent.assign(MAXN, -1);   // Reset parent array
    visited[1] = 1;

    while (!q.empty()) {
        int u = q.front();
        q.pop();

        if (u == n) {
            vector<int> path;
            while (u != -1) {  // Construct the path by following parents
                path.push_back(u);
                u = parent[u];
            }
            reverse(path.begin(), path.end());  // Reverse to get the path from 1 to n
            routes.push_back(path);  // Store the route
            return true;
        }

        for (int v : adj[u]) {
            if (!visited[v]) {
                visited[v] = 1;
                parent[v] = u;
                q.push(v);
            }
        }
    }
    return false;
}

int main() {
    int n, m;
    cin >> n >> m;

    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        adj[a].push_back(b);  // Add teleporter from room a to room b
    }

    int days = 0;
    while (bfs(n)) {  // Keep finding paths until no more paths exist
        days++;
        int u = n;
        while (parent[u] != -1) {  // Remove the edges used in the current path
            int p = parent[u];
            adj[p].erase(remove(adj[p].begin(), adj[p].end(), u), adj[p].end());
            u = p;
        }
    }

    cout << days << endl;  // Output the number of days
    for (const auto& route : routes) {
        cout << route.size() << endl;  // Output the size of each route
        for (int room : route) {
            cout << room << " ";  // Output the rooms in the current route
        }
        cout << endl;
    }

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: WRONG ANSWER