Submission #980219

#	Time	Username	Problem	Language	Result	Execution time	Memory
980219		nextgenxing	수천개의 섬 (IOI22_islands)	C++17	Compilation error	0 ms	0 KiB

islands

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

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define F0R(i, n) for(int i = 0; i < (n); i++)
#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define F0Rd(i, n) for(int i = (n)-1; i >= 0; i--)
#define FORd(i, a, b) for(int i = (b)-1; i >= (a); i--)
#define ff first 
#define ss second 
const int MAX_N = 2e5+5;
const ll MOD = 1e9+7;

vector<pii> adj[MAX_N];

bool dfs(int curr, int par, vector<int> &path){
    if(!adj[curr].size()) return false;
    if(curr){
        if(adj[curr].size() == 1) return false;
        if(adj[curr].size() > 2){
            if(adj[curr][0].ff == par){
                path.push_back(adj[curr][1].ss), path.push_back(adj[curr][1].ss^1);
                path.push_back(adj[curr][2].ss), path.push_back(adj[curr][2].ss^1);
                path.push_back(adj[curr][1].ss^1), path.push_back(adj[curr][1].ss);
                path.push_back(adj[curr][2].ss^1), path.push_back(adj[curr][2].ss);
            } else if(adj[curr][1].ff == par){
                path.push_back(adj[curr][0].ss), path.push_back(adj[curr][0].ss^1);
                path.push_back(adj[curr][2].ss), path.push_back(adj[curr][2].ss^1);
                path.push_back(adj[curr][0].ss^1), path.push_back(adj[curr][0].ss);
                path.push_back(adj[curr][2].ss^1), path.push_back(adj[curr][2].ss);
            } else{
                path.push_back(adj[curr][1].ss), path.push_back(adj[curr][1].ss^1);
                path.push_back(adj[curr][0].ss), path.push_back(adj[curr][0].ss^1);
                path.push_back(adj[curr][1].ss^1), path.push_back(adj[curr][1].ss);
                path.push_back(adj[curr][0].ss^1), path.push_back(adj[curr][0].ss);
            }
            return true;
        }
        bool ans;
        if(adj[curr][0].ff == par){
            path.push_back(adj[curr][1].ss);
            ans = dfs(adj[curr][1].ff, curr, path);
            path.push_back(adj[curr][1].ss);
        } else{
            path.push_back(adj[curr][0].ss);
            ans = dfs(adj[curr][0].ff, curr, path);
            path.push_back(adj[curr][0].ss);
        }
        return ans;
    } else{
        if(adj[curr].size() == 1){
            path.push_back(adj[curr][0].ss);
            bool ans = dfs(adj[curr][0].ff, curr, path);
            path.push_back(adj[curr][0].ss);
            return ans;
        }
        if(adj[curr].size() > 1){
            path.push_back(adj[curr][1].ss), path.push_back(adj[curr][1].ss^1);
            path.push_back(adj[curr][0].ss), path.push_back(adj[curr][0].ss^1);
            path.push_back(adj[curr][1].ss^1), path.push_back(adj[curr][1].ss);
            path.push_back(adj[curr][0].ss^1), path.push_back(adj[curr][0].ss);
            return true;
        }
    }
}

variant<bool, vector<int>> find_journey(int n, int m, vector<int> u, vector<int> v){
    if(n == 2){
        vector<int> num1, num2;
        F0R(i, m){
            if(u[i]) num2.push_back(i);
            else num1.push_back(i);
        }
        if(num1.size() < 2) return false;
        if(num2.size() < 1) return false;
        vector<int> ans;
        ans.push_back(num1[0]), ans.push_back(num2[0]), ans.push_back(num1[1]);
        ans.push_back(num1[0]), ans.push_back(num2[0]), ans.push_back(num1[1]);
        return ans;
    }
    if(n <= 400 && m == n*(n-1)){
        int a, b, c, d;
        F0R(i, m){
            if(u[i] == 0 && v[i] == 1) a = i;
            if(u[i] == 1 && v[i] == 0) b = i;
            if(u[i] == 0 && v[i] == 2) c = i;
            if(u[i] == 2 && v[i] == 0) d = i;
        }
        vector<int> ans;
        ans.push_back(a), ans.push_back(b), ans.push_back(c), ans.push_back(d);
        ans.push_back(b), ans.push_back(a), ans.push_back(d), ans.push_back(c);
        return ans;
    }
    if(n <= 1000){
        F0R(i, m) adj[u[i]].push_back({v[i], i});
        vector<int> ans;
        if(!dfs(0, -1, ans)) return false;
        return ans;
    }
}

int main() {
  int N, M;
  assert(2 == scanf("%d %d", &N, &M));

  std::vector<int> U(M), V(M);
  for (int i = 0; i < M; ++i) {
    assert(2 == scanf("%d %d", &U[i], &V[i]));
  }

  std::variant<bool, std::vector<int>> result = find_journey(N, M, U, V);
  if (result.index() == 0) {
    printf("0\n");
    if (std::get<bool>(result)) {
      printf("1\n");
    } else {
      printf("0\n");
    }
  } else {
    printf("1\n");
    std::vector<int> &canoes = std::get<std::vector<int>>(result);
    printf("%d\n", static_cast<int>(canoes.size()));
    for (int i = 0; i < static_cast<int>(canoes.size()); ++i) {
      if (i > 0) {
        printf(" ");
      }
      printf("%d", canoes[i]);
    }
    printf("\n");
  }
  return 0;
}

Compilation message (stderr)

islands.cpp: In function 'bool dfs(int, int, std::vector<int>&)':
islands.cpp:68:1: warning: control reaches end of non-void function [-Wreturn-type]
   68 | }
      | ^
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:103:1: warning: control reaches end of non-void function [-Wreturn-type]
  103 | }
      | ^
/usr/bin/ld: /tmp/ccbRwQhl.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccwnbhen.o:islands.cpp:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status