Distinct Routes

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

typedef long long ll;
const int N = 505;
ll n, m;
vector<vector<ll>> weigh(N, vector<ll>(N, 0));
vector<vector<ll>> adj(N);

ll flow = 0;
vector<ll> parent(N);
ll new_flow;
vector<vector<ll>> ans(N);

ll bfs(ll s, ll t, vector<ll>& parent) {
    fill(parent.begin(), parent.end(), -1);
    parent[s] = -999;
    queue<ll> q;
    q.push(s);

    while (!q.empty()) {
        ll cur = q.front();
        q.pop();

        for (ll next : adj[cur]) {
            if (parent[next] == -1 && weigh[cur][next] > 0) {
                parent[next] = cur;
                if (next == t) return 1;
                q.push(next);
            }
        }
    }
    return 0;
}

ll maxflow(ll s, ll t) {
    while ((new_flow = bfs(s, t, parent))) {
        flow++;
        ll cur = t;
        ans[flow].push_back(cur);
        while (cur != s) {
            ll prev = parent[cur];
            ans[flow].push_back(prev);
            weigh[prev][cur] --;
            weigh[cur][prev] ++;
            cur = prev;
        }
    }
    return flow;
}

void solve() {
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        ll a, b;
        cin >> a >> b;
        adj[a].push_back(b);
        adj[b].push_back(a);
        
        weigh[a][b]++;

    }
    int amount = maxflow(1, n);
    cout << amount << endl;
    for (int i = 1; i <= amount; i++) {
        cout << ans[i].size() << endl;;
        for (int j = ans[i].size() - 1; j >= 0; j--) cout << ans[i][j] << ' ';
        cout << endl;
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
 
    solve();
 
    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