Submission #1024752

#	Time	Username	Problem	Language	Result	Execution time	Memory
1024752		mansur	Thousands Islands (IOI22_islands)	C++17	Compilation error	0 ms	0 KiB

islands

#include "islands.h"
#include <bits/stdc++.h>
#include <variant>

using namespace std;

#define rall(s) s.rbegin(), s.rend()
#define all(s) s.begin(), s.end()
#define sz(s) (int) s.size()
#define s second 
#define f first 

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

const int N = 3e5;

vector<pii> g[N], pr(N);
vector<int> was(N), ans;

bool dfs(int u, int x) {
    was[u] = 1;
    if (sz(g[u]) > 1 + (u > 0)) {
        for (auto [to, id]: g[u]) {
            if (id == x) continue;
            ans.push_back(id);
            ans.push_back(id ^ 1);
        }
        for (auto [to, id]: g[u]) {
            if (id == x) continue;
            ans.push_back(id ^ 1);
            ans.push_back(id);
        }
        return true;
    }
    for (auto [to, id]: g[u]) {
        if (id == x) continue;
        ans.push_back(id);
        bool is = dfs(to, id ^ 1);
        ans.push_back(id);
        return is;
    }
    return false;
}

void fnd(int u) {
    was[u] = 1;
    for (auto [to, id]: g[u]) {
        if (!was[to]) {
            if (fnd(to)) return true;
        }else if (to == 0) {
            return true;
        }
    }
    return false;
}

variant<bool, vector<int>> find_journey(int n, int m, vector<int> u, vector<int> v) {
    bool okk = 1;
    for (int i = 0; i < m; i++) {
        if ((i & 1) && (u[i] != u[i - 1] || v[i] != v[i - 1])) okk = 0;
        g[u[i]].push_back({v[i], i});
    }
    if (n == 2) {
        if (sz(g[0]) > 1 && sz(g[1])) {
            vector<int> ans = {g[0][0].s, g[1][0].s, g[0][1].s, g[0][0].s, g[1][0].s, g[0][1].s};
            return ans;
        }
        return false;
    }
    if (okk) {
        return fnd(0);
    }
    if (n <= 400) {
        int a[n][n], ok = 1;
        for (int i = 0; i < n; i++) {
            if (sz(g[i]) != n - 1) ok = 0;
            for (auto [to, id]: g[i]) a[i][to] = id;
        }
        if (ok) {
            vector<int> ans = {a[0][1], a[1][2], a[2][0], a[0][2], a[2][1], a[1][0], a[2][0], a[1][2], a[0][1], a[1][0], a[2][1], a[0][2]};
            return ans;
        }
    }
    if (dfs(0, -1)) return ans;
    return false;
}

Compilation message (stderr)

islands.cpp: In function 'void fnd(int)':
islands.cpp:51:20: error: could not convert 'fnd(to)' from 'void' to 'bool'
   51 |             if (fnd(to)) return true;
      |                 ~~~^~~~
      |                    |
      |                    void
islands.cpp:51:33: error: return-statement with a value, in function returning 'void' [-fpermissive]
   51 |             if (fnd(to)) return true;
      |                                 ^~~~
islands.cpp:53:20: error: return-statement with a value, in function returning 'void' [-fpermissive]
   53 |             return true;
      |                    ^~~~
islands.cpp:56:12: error: return-statement with a value, in function returning 'void' [-fpermissive]
   56 |     return false;
      |            ^~~~~
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:73:19: error: could not convert 'fnd(0)' from 'void' to 'std::variant<bool, std::vector<int, std::allocator<int> > >'
   73 |         return fnd(0);
      |                ~~~^~~
      |                   |
      |                   void