#include<stdio.h>

int n,x,m;

bool f[1001];

int main()

{

scanf("%d",&n);

for (int i=1;i<=n;i++)

{

**scanf("%d",&x);

if (!f[x])

{

m++;

f[x]=true;

} **
}

printf("%d\n",m);

for (int i=1;i<1001;i++)

if (f[i])

printf("%d ",i);

return 0;

}

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn=105;

int n;
int a[maxn],f[maxn*10];

main()
{
memset(f,0,sizeof(f));
int x,k=0;
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>x;
if(f[x]==0)
{
f[x]=1;
a[++k]=x;
}
}
sort(a+1,a+k+1);
cout<<k<<endl;
for(int i=1;i<=k;i++)
cout<<a[i]<<' ';
cout<<endl;
return 0;
}

c++，low爆了
#include<iostream>
#include<fstream>
#include<algorithm>
using namespace std;
int x[1010],a,n;
int main()
{
//freopen("random.in","r",stdin);
//freopen("random.out","w",stdout);
cin>>n;
for(int i=0;i<n;i++) cin>>x[i];
sort(x,x+n);
for(int i=0;i<1000;i++) if(x[i]==x[i+1]) x[i]=0;
for(int i=0;i<1000;i++) if(x[i]) a++;
cout<<a<<endl;
for(int i=0;i<1000;i++) if(x[i]) cout<<x[i]<<" ";
return 0;
}

#include<iostream>
#include<set>
using namespace std;
int main(void)
{
    set<int>a;
    int n=0;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        int num=0;
        cin>>num;
        a.insert(num);
    }
    set<int>::iterator iter;
    cout<<a.size()<<endl;
    for(iter=a.begin();iter!=a.end();iter++)
    {
        cout<<*iter<<' ';
    }
} 

第一遍眼瞎没看到要输出个数。。。前几天用了一下map，今天看到这道题就想到了set（红黑树就是强，虽然我都不知道啥东西，

stl!!!

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<int> v;
    while (n--) {
        int num;
        cin >> num;
        if (count(v.begin(), v.end(), num) == 0)    // 在前面的输入中不存在 num 
            v.push_back(num);                       // 在 v 中加入 num 
    }
    sort(v.begin(), v.end());                       // 排序 
    cout << v.size() << endl;                       // v 的长度 
    for (size_t i = 0; i < v.size(); i++)           // 注意是 size_t (c++11) 
        cout << v[i] << " ";                        // 遍历输出 
    cout << endl;
    return 0;
}

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
int a[10000];
int main(){
int n;
scanf("%d",&n);
for(int i=1;i<=n;i++){
scanf("%d",&a[i]);
}
sort(a+1,a+1+n);
int count=n;
for(int i=1;i<n;i++){
for(int j=i+1;j<=n;j++){
if(a[i]==a[j] && a[j]!='*'){
a[j]='*';
count--;
}
}
}
cout<<count<<endl;
for(int i=1;i<=n;i++){
if(a[i]!='*'){
cout<<a[i]<<" ";
}
}
cout<<endl;
return 0;
}

#include<iostream>
#include<set>
#include<iterator>
using namespace std;
set<int> s;
int main()
{
    int m,n;
    cin>>m;
    for(int i=1;i<=m;i++)
    {
        cin>>n;
        s.insert(n);
    }
    cout<<s.size()<<endl;
    for(set<int>::iterator it=s.begin();it!=s.end();it++) cout<<*it<<' ';
    return 0;
}

测试数据 #0: Accepted, time = 0 ms, mem = 512 KiB, score = 10
测试数据 #1: Accepted, time = 0 ms, mem = 512 KiB, score = 10
测试数据 #2: Accepted, time = 0 ms, mem = 512 KiB, score = 10
测试数据 #3: Accepted, time = 0 ms, mem = 508 KiB, score = 10
测试数据 #4: Accepted, time = 0 ms, mem = 512 KiB, score = 10
测试数据 #5: Accepted, time = 0 ms, mem = 512 KiB, score = 10
测试数据 #6: Accepted, time = 0 ms, mem = 512 KiB, score = 10
测试数据 #7: Accepted, time = 0 ms, mem = 516 KiB, score = 10
测试数据 #8: Accepted, time = 0 ms, mem = 516 KiB, score = 10
测试数据 #9: Accepted, time = 0 ms, mem = 512 KiB, score = 10
Accepted, time = 0 ms, mem = 516 KiB, score = 100
代码
#include<cstdio>

const int N= 1003;
bool a[N];

int read(){
static char ch;
static int x;
for(ch= getchar(); ch<'0' || ch>'9'; ch= getchar());
for(x= ch-'0', ch= getchar(); ch>='0' && ch<='9'; x= x*10+ch-'0', ch= getchar());
return x;
}

int main(){
register int n;
n= read();
register int i;
for(i= 0; i<n; i++) a[read()]= 1;
n= 0;
for(i= 1; i<1001; i++) n+= a[i];
printf("%d\n", n);
for(i= 1; i<1001; i++) if(a[i]) printf("%d ", i);
return 0；
}
理论上没法再快了

这题简直就是为unique量身定做的。。。
```c++
#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;

const int maxn = 100 + 5;
int n;
int num[maxn];

int main ()
{
cin >> n;
for (int i = 0; i < n; i++) cin >> num[i];
sort(num, num+n);
int m = unique(num, num+n) - num;
cout << m << "\n";
for (int i = 0; i < m; i++) cout << num[i] << " ";
return 0;
}
```

foo.cpp:5:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
main()
^
测试数据 #0: Accepted, time = 15 ms, mem = 560 KiB, score = 10
测试数据 #1: Accepted, time = 15 ms, mem = 556 KiB, score = 10
测试数据 #2: Accepted, time = 0 ms, mem = 560 KiB, score = 10
测试数据 #3: Accepted, time = 0 ms, mem = 560 KiB, score = 10
测试数据 #4: Accepted, time = 0 ms, mem = 560 KiB, score = 10
测试数据 #5: Accepted, time = 15 ms, mem = 556 KiB, score = 10
测试数据 #6: Accepted, time = 0 ms, mem = 556 KiB, score = 10
测试数据 #7: Accepted, time = 0 ms, mem = 560 KiB, score = 10
测试数据 #8: Accepted, time = 0 ms, mem = 560 KiB, score = 10
测试数据 #9: Accepted, time = 0 ms, mem = 556 KiB, score = 10
Accepted, time = 45 ms, mem = 560 KiB, score = 100
为何不能秒杀？！

var i,j,k,n,l,t:longint;
a:array[1..10000] of longint;
begin
read(n);
k:=n;
for i:=1 to k do
begin
read(l);
a[l]:=a[l]+1;
if a[l]>1 then
begin
a[l]:=1;
n:=n-1;
end;
end;
writeln(n);
for i:=1 to 1000 do
begin
if a[i]=1 then inc(t);
if t=n then
begin
writeln(i);
break;
end;
if a[i]=1 then write(i,' ');
end;
end.

#include<iostream>
using namespace std;
int n,t,count,a[1001];
int main()
{
cin>>n;
for(int i=0;i<n;i++)
{
cin>>t;
a[t]++;
}
for(int i=0;i<1000;i++)
{
if(a[i]>0)
count++;
}
cout<<count<<endl;
for(int i=0;i<1000;i++)
{
if(a[i]>0)cout<<i<<" ";
}
return 0;
}

排序经典老题
var
n,i,num:longint;
s,a:array[1..100000] of longint;
procedure qsort(l,r:longint);
var
i,j,p,mid:longint;
begin
i:=l; j:=r;
mid:=a[(l+r) div 2];
repeat
while a[i]<mid do inc(i);
while a[j]>mid do dec(j);
if i<=j then begin
p:=a[i];
a[i]:=a[j];
a[j]:=p;
inc(i);
dec(j);
end;
until i>j;
if l<j then qsort(l,j);
if i<r then qsort(i,r);
end;
begin
readln(n);
for i:=1 to n do read(a[i]);
readln;
qsort(1,n);
num:=1;
s[1]:=a[1];
for i:=1 to n do begin
if s[num]<>a[i] then begin
num:=num+1;
s[num]:=a[i];
end;
end;
writeln(num);
for i:=1 to num do begin
write(s[i],' ');
end;
end.

测试数据 #0: Accepted, time = 0 ms, mem = 804 KiB, score = 10
测试数据 #1: Accepted, time = 0 ms, mem = 804 KiB, score = 10
测试数据 #2: Accepted, time = 15 ms, mem = 804 KiB, score = 10
测试数据 #3: Accepted, time = 15 ms, mem = 804 KiB, score = 10
测试数据 #4: Accepted, time = 0 ms, mem = 804 KiB, score = 10
测试数据 #5: Accepted, time = 0 ms, mem = 804 KiB, score = 10
测试数据 #6: Accepted, time = 0 ms, mem = 804 KiB, score = 10
测试数据 #7: Accepted, time = 0 ms, mem = 804 KiB, score = 10
测试数据 #8: Accepted, time = 15 ms, mem = 804 KiB, score = 10
测试数据 #9: Accepted, time = 0 ms, mem = 808 KiB, score = 10
Accepted, time = 45 ms, mem = 808 KiB, score = 100

var a:array[1..100] of integer;
b:array[1..1000] of integer;
s,i,n:integer;
begin
readln(n);
for i:=1 to n do read(a[i]);
readln;
for i:=1 to n do b[a[i]]:=1;
s:=0;
for i:=1 to 1000 do if b[i]=1 then inc(s);
writeln(s);
for i:=1 to 1000 do if b[i]=1 then write(i,' ');
writeln;
end.

测试数据 #0: Accepted, time = 0 ms, mem = 492 KiB, score = 10

测试数据 #1: Accepted, time = 0 ms, mem = 492 KiB, score = 10

测试数据 #2: Accepted, time = 0 ms, mem = 488 KiB, score = 10

测试数据 #3: Accepted, time = 0 ms, mem = 492 KiB, score = 10

测试数据 #4: Accepted, time = 0 ms, mem = 492 KiB, score = 10

测试数据 #5: Accepted, time = 0 ms, mem = 492 KiB, score = 10

测试数据 #6: Accepted, time = 0 ms, mem = 488 KiB, score = 10

测试数据 #7: Accepted, time = 0 ms, mem = 496 KiB, score = 10

测试数据 #8: Accepted, time = 0 ms, mem = 492 KiB, score = 10

测试数据 #9: Accepted, time = 0 ms, mem = 492 KiB, score = 10

include <stdio.h>

int a[1001];

int main (void)
{
int n, i, val, cnt, flag;
scanf("%d",&n);
for (i=0, cnt=0; i<n; i++) {
scanf("%d",&val);
if (a[val] == 0)
cnt++;
a[val]++;
}
printf("%d\n",cnt);
for (i=1,flag=1; i<1001; i++) {
if (flag && a[i]!=0) {
printf("%d",i);
flag = 0;
}
else if (a[i]!=0) {
printf(" %d",i);
}
}

putchar('\n');
return 0;
}
数据量不大用桶排序

var
a:array[1..101] of integer;
n,i,x:integer;
procedure qsort(head,tail:integer);
var
mid,i,j,temp:integer;
begin
mid:=a[(head+tail)div 2];
i:=head;
j:=tail;
while i<=j do begin
while a[i]<mid do inc(i); while a[j]>mid do dec(j);
if i<=j then begin
temp:=a[i]; a[i]:=a[j]; a[j]:=temp; inc(i); dec(j); end;
end;
if head<j then qsort(head,j); if tail>i then qsort(i,tail);
end;
begin
readln(n);
For i:=1 to n do
read(a[i]);
readln;
qsort(1,n);
x:=n;
For i:=2 to n do
if a[i]=a[i-1] then x:=x-1;
writeln(x);
write(a[1],' ');
For i:=2 to n do
if a[i]<>a[i-1] then write(a[i],' ');
writeln;
readln;
end.

var
a:array[1..101] of integer;
n,i,x:integer;
procedure qsort(head,tail:integer);
var
mid,i,j,temp:integer;
begin
mid:=a[(head+tail)div 2];
i:=head;
j:=tail;
while i<=j do begin
while a[i]<mid do inc(i); while a[j]>mid do dec(j);
if i<=j then begin
temp:=a[i]; a[i]:=a[j]; a[j]:=temp; inc(i); dec(j); end;
end;
if head<j then qsort(head,j); if tail>i then qsort(i,tail);
end;
begin
readln(n);
For i:=1 to n do
read(a[i]);
readln;
qsort(1,n);
x:=n;
For i:=2 to n do
if a[i]=a[i-1] then x:=x-1;
writeln(x);
write(a[1],' ');
For i:=2 to n do
if a[i]<>a[i-1] then write(a[i],' ');
writeln;
readln;
end.

include<iostream>
using namespace std;
int N;
int i;
int x;
int a[1001];
int sum;
int main()
{
cin>>N;
for(i=0;i<N;i++) { cin>>x;
a[x]++;
}
for(i=0;i<=1000;i++)
{
if(a[i]>0)
sum++;
}
cout<<sum<<endl; for(i=0;i<=1000;i++) { if(a[i]>0)
cout<<i<<" ";
}
return 0;
}

var k,n,i:longint;
a,s:array[1..100] of longint;
b:set of 1..100;

begin
readln(n);
for i:=1 to n do
read(a[i]);
for i:=1 to n do
b:=b+[a[i]];
k:=1;
for i:=1 to 1000 do
if i in b then
begin
s[k]:=i;
inc(k);
end;
n:=k-1;
for i:=1 to n do
write(s[i],' ');
readln;
readln;
end.

var a,b:array[1..10000]of integer;
t,N,i,j:integer;
procedure suiji(head,tail:integer);
var i,j,empty,mid:integer;
begin
i:=head;j:=tail;mid:=a[(head+tail)div 2];
while (i<=j) do
begin
while a[i]<mid do inc(i);
while a[j]>mid do dec(j);
if i<=j then begin
empty:=a[i]; a[i]:=a[j]; a[j]:=empty;
inc(i); dec(j);
end;
end;
if i<tail then suiji(i,tail);
if j>head then suiji(head,j);
end;

begin
t:=0;
readln(N);
for i:=1 to N do
read(a[i]);
for i:=1 to N-1 do
for j:=i+1 to N do
if a[i]=a[j]
then begin a[j]:=0; t:=t+1; end;
writeln(N-t+1);
suiji(1,N);
for i:=1 to N do
if a[i]<>0 then write(a[i],' ');
end.