这道题可以不用bfs

#include<bits/stdc++.h>

#define db double

#define st string

#define ct const

#define ll long long

#define xh(a,b,c) for(int a=b;a<=c;a++)

#define wx while(1)

#define dn(a,b,c) for(int a=b;a>=c;a--)

using namespace std;

ll n,a[200010];

ll sum;

signed main(){

cin>>n;

xh(i,1,n)cin>>a[i];

sort(a+1,a+n+1);

a[++n]=a[n]+1;

sum=1;

for(int i=2;i<=n;i++){

if(a[i]!=a[i-1])cout<<a[i-1]<<' '<<sum<<endl,sum=1;

else sum++;

}

return 0;

}