Language: C++


// Problem : D - Friends
// Contest : AtCoder - AtCoder Beginner Contest 177
// URL : https://atcoder.jp/contests/abc177/tasks/abc177_d
// Memory Limit : 1024 MB
// Time Limit : 2000 ms
// Powered by CP Editor (https://github.com/cpeditor/cpeditor)


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


#define sc(ar,n) for(int pen=0;pen<n;pen++){ cin>>ar[pen];}
#define pr(ar,n) for(int pen=0;pen<n;pen++){ cout<<ar[pen]<<" ";} cout<<endl;
#define mem(ar,x) memset(ar,x,sizeof(ar))
#define fastio ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define mod 1000000007
#define rt return 0;
#define ct continue;
#define pb push_back
#define ll long long int
#define ff first
#define ss second
#define mod 1000000007
#define maxn 1000003
#define all(x) x.begin(),x.end()
#define sz(x) (int)x.size()
#define rep(i, begin, end) for (__typeof(end) i = (begin) - ((begin) > (end)); i != (end) - ((begin) > (end)); i += 1 - 2 * ((begin) > (end)))

void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

vector<ll>adj[maxn];
ll vis[maxn];
ll size;

void dfs(ll node){
	vis[node] = 1;
	size++;
	
	for(ll child:adj[node]){
		if(!vis[child])dfs(child);
	}
}

int main(){
	
	fastio;
	ll n,m,a,b;
	cin>>n>>m;
	ll ans=0;
	

	for(int i=0;i<m;i++){
		cin>>a>>b;
		
		adj[a].pb(b);
		adj[b].pb(a);
		
	}
	for(int i=1;i<=maxn;i++){
		if(!vis[i])
		{
	    ans=max(ans,size);
		size=0;
		dfs(i);
					
		}
	}
	cout<<ans;
	
	}


	
	
	
	



Compiler output:
a.cc: In function 'void dfs(long long int)':
a.cc:64:9: error: reference to 'size' is ambiguous
   64 |         size++;
      |         ^~~~
In file included from /usr/include/c++/14/string:53,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:10:
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:60:4: note:                 'long long int size'
   60 | ll size;
      |    ^~~~
a.cc: In function 'int main()':
a.cc:89:25: error: reference to 'size' is ambiguous
   89 |             ans=max(ans,size);
      |                         ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:60:4: note:                 'long long int size'
   60 | ll size;
      |    ^~~~
a.cc:90:17: error: reference to 'size' is ambiguous
   90 |                 size=0;
      |                 ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:60:4: note:                 'long long int size'
   60 | ll size;
      |    ^~~~