Submission #1076980

#	Time	Username	Problem	Language	Result	Execution time	Memory
1076980		mariaclara	Thousands Islands (IOI22_islands)	C++17	0 / 100	1 ms	604 KiB

islands

#include "islands.h"
#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair<int,int> pii;
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
#define pb push_back
#define mk make_pair
#define fr first
#define sc second
 
vector<int> vis, block, at;
vector<vector<pii>> edges;

vector<int> dfs(int x) {
    vis[x] = 1;
 
    for(auto [viz,ind] : edges[x]) {
        if(block[viz]) continue;
        if(vis[viz]) {
            at.pb(ind);
            return at;
        }
        at.pb(ind);
        vector<int> v = dfs(viz);
        if(!v.empty()) return v;
    }

    block[x] = 1;
    return {};
}
variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
    edges.resize(N);
    vis.resize(N);
    block.resize(N);
 
    for(int i = 0; i < M; i += 2)  edges[U[i]].pb({V[i], i});
 
    vector<int> c = dfs(0), ans;
    if(c.empty()) return false;

    int x = V[c.back()], m;

    for(int i = sz(c) - 1; i >= 0; i--) if(U[i] == x) m = i;

    ans = c;
    for(int i = m-1; i >= 0; i--) ans.pb(c[i]);
    for(int i = 0; i < m; i++) ans.pb(c[i] + (i == 0));
    for(int i = sz(c) - 1; i >= m; i--) ans.pb(c[i]);
    for(int i = m-1; i >= 0; i--) ans.pb(c[i] + (i == 0));
}

Compilation message (stderr)

islands.cpp: In function 'std::variant<bool, std::vector<int, std::allocator<int> > > find_journey(int, int, std::vector<int>, std::vector<int>)':
islands.cpp:42:26: warning: control reaches end of non-void function [-Wreturn-type]
   42 |     vector<int> c = dfs(0), ans;
      |                          ^

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