解答代碼

#include<iostream>#include<cstdio>#include<string>#include<cstring>#include<algorithm>using namespace std;int main(){	int i,k,n,flag=0,ans=0,pos;	cin>>n;	getchar();	char *s=(char *)malloc(sizeof(char)*n);	gets(s);	int end=n-1;	pos=0;	for(i=0;i<end;i++)	{		for(k=end;k>=0;k--)		{			if(k==i)			{				flag++;				if(n%2==0 || flag>1)				{					cout<<"Impossible"<<endl;					return 0;				}				pos=n/2-i;				break;			}			else if(s[k]==s[i])			{				ans+=end-k;				for(int index=k;index<end;index++)					s[index]=s[index+1];				s[end]=s[i];				end--;				break;			}		}	}	cout<<ans+pos<<endl;	return 0;}