Submission #1086128

#	Time	Username	Problem	Language	Result	Execution time	Memory
1086128		SamueleVid	Thousands Islands (IOI22_islands)	C++17	0 / 100	21 ms	8056 KiB

islands

#include <bits/stdc++.h>
using namespace std;
 
constexpr int MAXN = 1e5 + 5;
vector<int> adj[MAXN];
bool v[MAXN];
 
bool ciclo = 0;
 
void dfs(int u) {
    // cout << "u, p " << u << " " << p << '\n';
    // toposort: is there a cycle ?
    if (v[u] == 2) return;
    if (v[u] == 1) {
        ciclo = 1;
        return;
    }
    v[u] = 1;
 
    for (auto x : adj[u]) {
        dfs(x);
        if (ciclo) return;   
    }
 
    v[u] = 2;
}   

variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
    fill(v, v + MAXN, 0);
    for (int i = 0; i < M; i ++) {
        adj[U[i]].push_back(V[i]); // no stesso arco sennò diventa non lineare sui nodi
    }
 
    dfs(0);
    return ciclo;
}

Compilation message (stderr)

islands.cpp: In function 'void dfs(int)':
islands.cpp:13:14: warning: comparison of constant '2' with boolean expression is always false [-Wbool-compare]
   13 |     if (v[u] == 2) return;
      |         ~~~~~^~~~

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