Submission #890879

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Source Code Expand

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

#define FOR(i,a,b) for(int i=a;i<b;i++)
#define REP(i,b) FOR(i,0,b)
#define MP make_pair
#define PB push_back
#define REACH cerr<<"reached line "<<__LINE__<<endl
#define DBG(x) cerr<<"line "<<__LINE__<<" "<<#x<<":"<<x<<endl

using uint=unsigned int;
using ll=long long;
using pii=pair<int,int>;
using vi=vector<int>;
using ld=long double;

template<class T,class U>
ostream& operator<<(ostream& os,const pair<T,U>& p){
	os<<"("<<p.first<<","<<p.second<<")";
	return os;
}

template<class T>
ostream& operator <<(ostream& os,const vector<T>& v){
	os<<"[";
	REP(i,(int)v.size()){
		if(i)os<<",";
		os<<v[i];
	}
	os<<"]";
	return os;
}

int read(){
	int i;
	scanf("%d",&i);
	return i;
}

template<class T>
void chmax(T& a,T b){
	a=max(a,b);
}

template<class T>
void chmin(T& a,T b){
	a=min(a,b);
}

template<class T>
void ResetVector(vector<T>& v,int n,const T& t){
	v.clear();
	v.resize(n,t);
}

int main(){
	int n=read();
	vi like(n);
	REP(i,n)
		like[i]=read()-1;
	int ans=0;
	REP(i,n)
		if(like[like[i]]==i)
			ans++;
	cout<<ans/2<<endl;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int read()’:
./Main.cpp:36:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&i);
                ^

Judge Result