Submission #2526977

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Source Code Expand

#include <cstdio>
#include <vector>
#define repi(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,a) repi(i,0,a)

using ll = long long;

ll N, M;
std::vector<int> G[100000];
int col[100000];

bool dfs( int v, int c )
{
  bool ret = true;

  col[v] = c;

  for( auto &u : G[v] )
  {
    if( col[u] == c )
      return false;
    if( !col[u] )
      ret &= dfs( u, -c );
  }

  return ret;
}

int main()
{
  scanf( "%lld%lld", &N, &M );
  rep( i, M )
  {
    int A, B;
    scanf( "%d%d", &A, &B );
    --A; --B;
    G[A].push_back( B );
    G[B].push_back( A );
  }

  bool bi = dfs( 0, 1 );

  if( bi )
  {
    ll B = 0, W = 0;

    rep( i, N )
    {
      if( col[i] == 1 )
        ++W;
      else
        ++B;
    }

    printf( "%lld\n", B*W-M );
  }
  else
    printf( "%lld\n", N*(N-1)/2-M );

  return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:31:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf( "%lld%lld", &N, &M );
                              ^
./Main.cpp:35:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf( "%d%d", &A, &B );
                            ^

Judge Result