Submission #1135133

#	Time	Username	Problem	Language	Result	Execution time	Memory
1135133		Lemser	Thousands Islands (IOI22_islands)	C++20	5 / 100	18 ms	5192 KiB

islands

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

using ll = long long;
using ull = unsigned long long;
using lld = long double;
using ii = pair<int,int>;
using pll = pair<ll, ll>;

using vi = vector<int>;
using vll = vector<ll>;
using vii = vector<ii>;
using vpll = vector<pll>;
using vlld = vector<lld>;

// #define endl '\n'
#define all(x) x.begin(),x.end()
#define lsb(x) x&(-x)
#define gcd(a,b) __gcd(a,b)
#define sz(x) (int)x.size()
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define fls cout.flush()

#define fore(i,l,r) for(auto i=l;i<r;i++)
#define fo(i,n) fore(i,0,n)
#define forex(i,r,l) for(auto i=r; i>=l;i--)
#define ffo(i,n) forex(i,n-1,0)

bool cmin(ll &a, ll b) { if(b<a){a=b;return 1;}return 0; }
bool cmax(ll &a, ll b) { if(b>a){a=b;return 1;}return 0; }
void valid(ll in) { cout<<((in)?"Yes\n":"No\n"); }
ll lcm(ll a, ll b) { return (a/gcd(a,b))*b; }
ll gauss(ll n) { return (n*(n+1))/2; }

const ll INF = 1e18;
const int N = 1005;

ll vis[N], dp[N], ans;
stack<ll> stk, rs;
vector<vector<array<ll, 2>>> gr;
vector<int> r;

void dfs (ll u, ll pr) {
  if (sz(r)) return;
  stk.push(u);
  rs.push(pr);
  vis[u] = 1;
  for (auto [v, i]: gr[u]) {
    if (vis[v]) {
      // cout << "OKKK\n";
      // exit(0);
      ans = 1;
      vll clrs;
      clrs.pb(i);
      while (sz(stk) && stk.top() != v) {
        clrs.pb(rs.top());
        stk.pop();
        rs.pop();
      }
      reverse(all(clrs));
      ll ot = (clrs[0]&1 ? clrs[0]-1 : clrs[0]+1);
      vll B;
      while (rs.top() != -1) {
        B.pb(rs.top());
        rs.pop();
      }
      reverse(all(B));
      for (ll i: B) r.pb(i);
      fo (x, sz(clrs)-1) {
        for (ll i: clrs) r.pb(i);
        r.pb(ot);
      }
      r.pb(clrs[0]);
      reverse(all(B));
      for (ll i: B) r.pb(i);
      return;
    } else {
      if (dp[v]) continue;
    if (sz(r)) return;
      dfs(v, i);
    }
  }
  if (sz(r)) return;
  dp[u] = 1;
  vis[u] = 0;
  stk.pop();
  rs.pop();
}

variant<bool, vector<int>> find_journey(
    int n, int m, vector<int> u, vector<int> v) {
  if (n == 2) {
    vll ok[2];
    fo (i, m) ok[u[i]].pb(i);
    if (sz(ok[0]) < 2 || sz(ok[1]) < 1) return false;
    vector<int> r;
    r.pb(ok[0][0]);
    r.pb(ok[1][0]);
    r.pb(ok[0][1]);
    r.pb(ok[0][0]);
    r.pb(ok[1][0]);
    r.pb(ok[0][1]);
    return r;
  }
  gr = vector<vector<array<ll, 2>>>(n);
  for (ll i = 0; i < m ; i += 2) {
    gr[u[i]].pb({v[i], i});
  }
  ans = 0;
  dfs(0, -1);
  if (ans == 0) return false;
  return r;
}

• Subtask 1: 5 / 5
• Subtask 2: 0 / 5
• Subtask 3: 0 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 45