set 轻松AC
```c++
#include<iostream>
#include<set>
using namespace std;
int main(){
int n;
cin>>n;
set<int> b;
for(int i=1;i<=n;i++){
int x;
cin>>x;
b.insert(x);
}
cout<<b.size()<<endl;
int j=b.size();
for(int i=1;i<=j;i++){
int x=*b.begin();
cout<<x<<' ';
b.erase(*b.begin());
}

}
```

program p1316;
var a:array[1..1000] of boolean;s:array[1..100] of longint;
i,n:longint;
begin
readln(n);fillchar(a,sizeof(a),false);
for i:=1 to n do
begin
read(s[i]);
a[s[i]]:=true;
end;
writeln(n);
for i:=1 to 1000 do
begin
if a[i] then write(i);
end;
end.

#include<math.h>
using namespace std;
int a[1000];
int main()
{
int i,j,k,n,t=0;
cin>>n;
for(i=0;i<n;i++)
cin>>a[i];
for(i=0;i<n;i++)
for(j=i+1;j<n;j++)
if(a[i]==a[j])
a[j]=0;

for(i=0;i<n;i++)
for(j=i+1;j<n;j++)
if(a[i]>a[j])
swap(a[i],a[j]);
for(i=0;i<n;i++)
if(a[i]!=0)
t++;
cout<<t<<endl;
for(i=0;i<n;i++)
if(a[i]!=0)
cout<<a[i]<<" ";
return 0;
}

#include <set>
#include <cstdio>
using namespace std;
int n,tmp;
set<int> S;
set<int>::iterator it;
int main(){
    scanf("%d",&n);
    for (int i=1;i<=n;i++){
        scanf("%d",&tmp);
        S.insert(tmp);
    }
    printf("%d\n",S.size());
    for (it=S.begin();it!=S.end();it++) printf("%d ",*it);
}

花式AC之set

include <cstdio> include <cstring> include <algorithm>
using namespace std;
int main()
{
int n,a[101],c[101],i,j,m=0;
bool b[1001]={0};
cin>>n;
for (i=0;i<n;i++) { cin>>a[i];
if (b[a[i]]==0)
{
c[m]=a[i];
m++;
b[a[i]]=1;
}
}
sort(c+0,c+m);
cout<<m<<endl;
for (i=0;i<m;i++)
cout<<c[i]<<" ";
}```
水水水淼

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int main()
{
    int n,a[101],c[101],i,j,m=0; 
    bool b[1001]={0};
    cin>>n;
    for (i=0;i<n;i++)
    {
        cin>>a[i];
        if (b[a[i]]==0)
        {
            c[m]=a[i];
            m++;
            b[a[i]]=1;
        }
    }
    sort(c+0,c+m);
    cout<<m<<endl; 
    for (i=0;i<m;i++)
    cout<<c[i]<<" ";
}```
水水水淼

#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
int a[100],m,x,k,j,l=0,t,b=0;
cin>>m;
for(int i=1;i<=m;++i)
cin>>a[i];

for(int i=1;i<=m-1;i++)
{
k=i;
for(int j=i+1;j<=m;j++)
if(a[k]>a[j]) k=j;
if(k!=i)
{
t=a[i];
a[i]=a[k];
a[k]=t;
}
}

for(int i=1;i<=m-1;i++)
{
k=i;
for(int j=i+1;j<=m;j++)
if(a[k]==a[j])

{a[k]=0; b+=1;}

}
cout<<m-b<<endl;
for(int i=1;i<=m;++i)
{
if(a[i]!=0)
cout<<a[i]<<" ";
}

}

直接用桶排序搞定，sort什么的对于这道题太复杂！
//超短
#include<iostream>
#define f for(int i=1;i<=n;++i)
using namespace std;
bool a[1001];
int s,q,n;
int main()
{
cin>>n;
f
{
cin>>s;
a[s]=1;
}
n=1000;
f if(a[i]) q++;
cout<<q<<endl;
f if(a[i]) cout<<i<<" ";
cout<<endl;
}

#include<stdio.h>
int a[100];
int main()
{
int n,i,j,temp;
scanf("%d",&n);
for(i=1;i<=n;i++)
scanf("%d",&a[i]);
for(i=1;i<=n-1;i++)
for(j=1;j<=n-i;j++)
if(a[j]<a[j-1])
{
temp=a[j];
a[j]=a[j-1];
a[j-1]=temp;
}
for(j=1;j<=n;j++)
printf("%d",a[j]);
return 0;
}

#include<iostream>
#include<algorithm>
using namespace std;
int main(){
  int n;
  scanf("%d",&n);
  int f=n;
  int a[n];
  for(int i=0;i<n;i++)scanf("%d",a+i);
  for(int i=0;i<n;i++){
    for(int j=i+1;j<n;j++){
        if(i!=j && a[i]==a[j] && a[i]!=-1 && a[j]!=-1 )f--,a[j]=-1;
      }
  }
  sort(a,a+n);
  printf("%d\n",f);
  for(int i=0;i<n;i++){
    if(a[i]!=-1)printf("%d ",a[i]);
  }
  return 0;
}

秒杀！
c++
#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
int a[105],n,i,x;
cin>>n; for(i=0;i<n;i++) cin>>a[i];
sort(a,a+n); x=unique(a,a+n)-a;
cout<<x<<endl; for(int i=0;i<x;i++) cout<<a[i]<<" ";
return 0;
}


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