#include <iostream>
using namespace std;int removeduplicate(int a[],int n)
{if (n==0){return 0;}int count=1;int index=0;for (int i = 1; i < n; i++){if (a[index]==a[i]){if (count<2){index++;a[index]=a[i];count++;}}else{index++;a[index]=a[i];count=1;}}return index+1;
}int removeduplicate2(int a[],int n)
{if (n==0){return 0;}int index=0;int i;for (i = 0; i < n; i++){if (i>0&&i<n-1&&a[i]==a[i-1]&&a[i]==a[i+1]){continue;}a[index]=a[i];index++;}return index;}

#include <iostream>
#include <algorithm>using namespace std;int removeduplicate(int a[],int n)
{sort(a,a+n);if (n==0){return 0;}int count=1;int index=0;for (int i = 1; i < n; i++){if (a[index]==a[i]){if (count<2){index++;a[index]=a[i];count++;}}else{index++;a[index]=a[i];count=1;}}return index+1;
}int removeduplicate2(int a[],int n)
{sort(a,a+n);if (n==0){return 0;}int index=0;int i;for (i = 0; i < n; i++){if (i>0&&i<n-1&&a[i]==a[i-1]&&a[i]==a[i+1]){continue;}a[index]=a[i];index++;}return index;}int main()
{int a[6]={1,2,1,2,1,3};int ans=removeduplicate(a,6);cout<<ans<<endl;int b[6]={1,2,1,2,1,3};int ans1=removeduplicate2(b,6);cout<<ans1<<endl;return 0;
}

#include <iostream>#include <map>
using namespace std;/*typedef std::map<int,int> MAP;
MAP my_map;*/
map<int,int> my_map;
int removeduplicate(int a[],int n)
{int i;int index=0;for (i = 0; i < n; i++){if (my_map[a[i]]<2){my_map[a[i]]++;a[index++]=a[i];}elsecontinue;}return index;
}int main()
{int a[6]={1,2,1,2,1,3};int ans=removeduplicate(a,6);cout<<ans<<endl;return 0;
}