Submission #777642

#	Time	Username	Problem	Language	Result	Execution time	Memory
777642		alexander707070	Thousands Islands (IOI22_islands)	C++17	Compilation error	0 ms	0 KiB

islands

#include<bits/stdc++.h>
#include <variant>
#define MAXN 200007
using namespace std;

int n,m;
vector< pair<int,int> > v[MAXN];
vector<int> path,sol;
int ind[MAXN];
bool vis[MAXN];

void euler(int x,int e){

    for(int i=ind[x];i<v[x].size();i++){
        ind[x]++;
        if(v[x][i].second<0 and !vis[-v[x][i].second]){
            swap(v[x][i],v[x][v[x].size()-1]); i--; continue;
        }

        euler(v[x][i].first,v[x][i].second);

        i=max(i,ind[x]-1);
    }

    path.push_back(e);
}

vector<int> ll,rr;

variant<bool, vector<int> > find_journey(int N, int M, vector<int> U, vector<int> V){
    n=N; m=M;

    if(n==2){
        if(m<=2)return false;
        return {}
    }

    for(int i=0;i<m;i++){
        U[i]++; V[i]++;

        if(U[i]<V[i]){
            ll.push_back(i);
        }else{
            rr.push_back(i);
        }

        v[U[i]].push_back({V[i],i});
    }

    if(n==2){
        if(int(ll.size())<2 or int(rr.size())<1)return false;
        return {ll[0],rr[0],ll[1],ll[0],rr[0],ll[1]};
    }

    for(int i=0;i<m;i++){
        v[V[i]].push_back({U[i],-i});
    }

    euler(1,-1);

    path.pop_back();
    reverse(path.begin(),path.end());

    for(int i=0;i<path.size();i++){
        sol.push_back(path[i]);
    }

    if(sol.empty())return false;
    return sol;
}

/*
int main(){
    find_journey(6, 7, {0,1,2,2,3,4,5}, {1,2,3,5,4,2,0});
}
*/

Compilation message (stderr)

islands.cpp: In function 'void euler(int, int)':
islands.cpp:14:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |     for(int i=ind[x];i<v[x].size();i++){
      |                      ~^~~~~~~~~~~~
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:35:18: error: expected ';' before '}' token
   35 |         return {}
      |                  ^
      |                  ;
   36 |     }
      |     ~             
islands.cpp:52:52: error: could not convert '{ll.std::vector<int>::operator[](0), rr.std::vector<int>::operator[](0), ll.std::vector<int>::operator[](1), ll.std::vector<int>::operator[](0), rr.std::vector<int>::operator[](0), ll.std::vector<int>::operator[](1)}' from '<brace-enclosed initializer list>' to 'std::variant<bool, std::vector<int, std::allocator<int> > >'
   52 |         return {ll[0],rr[0],ll[1],ll[0],rr[0],ll[1]};
      |                                                    ^
      |                                                    |
      |                                                    <brace-enclosed initializer list>
islands.cpp:64:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   64 |     for(int i=0;i<path.size();i++){
      |                 ~^~~~~~~~~~~~