Distinct Routes

// #ifdef ONLINE_JUDGE
// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
// #endif
#include "bits/stdc++.h"
#define fast ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define fill(arr,val) memset(arr,val,sizeof(arr))
#define FOR(i, a, b) for(__typeof(b) i = a, _b = b; i <= _b; ++i)
#define FORD(i, a, b) for(__typeof(a) i = a, _b = b; i >= _b; --i)
#define ALL(a) (a).begin(), (a).end()
#define YES cout << "YES\n"
#define NO cout << "NO\n"
#define ll long long
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define ii pair<int,int>
#define iii pair<int,pair<int,int>>
#define dq deque<int>
#define nend '\n'
using namespace std;

const ll inf = 1e18;
const int dx[] = {1,0,-1,0};
const int dy[] = {0,1,0,-1};
const int MOD = 1e9 + 7;
const ll hashi = 2e9 + 11;

void init_code() {
    fast;
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif
}
const int N=505, M=2005;
int n,m,to[M],cap[M],cnt=0;
bool vis[N];
vector<int> g[N];
void add(int a, int b) {
    to[cnt] = b; cap[cnt] = 1; g[a].pb(cnt++);
    to[cnt] = a; cap[cnt] = 0; g[b].pb(cnt++);
}
bool dfs(int u) {
    if (u == n) return 1;
    vis[u]=1;
    for (auto e: g[u]) {
        if (cap[e] && !vis[to[e]] and dfs(to[e])) {
            cap[e]--; cap[e^1]++;
            return 1;
        }
    }
    return 0;
}

void solve() {
    cin >> n >> m;
    FOR(i,1,m) {
        int a,b; cin >> a >> b;
        add(a,b);
    }

    int k = 0;
    while (1) {
        fill(vis, 0);
        if (!dfs(1)) break;
        k++;
    }

    cout << k << nend;
    FOR(i,1,k) {
        vector<int> path = {1};
        int u = 1;
        while (u != n) {
            for (auto e: g[u]) if (e % 2 == 0 and cap[e] == 0) {
                cap[e] = 1; ///consumed
                u = to[e];
                break;
            }
            path.pb(u);
        }
        cout << path.size() << nend;
        for (auto v: path) cout << v << ' ';
        cout << nend;
    }
}

int main() {
    init_code();

    int t = 1;
    // cin >> t;
    while (t--) {
        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: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED