字符串处理

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<queue>
#include<vector>
#include<cstring>
#include<cmath>
#include<map>
using namespace std;
typedef long long ll;
#define N 2011111
char str[1111];
int s[1111],f[1111][4],d[1111],b[1111];
int main()
{
    int t,k;
    cin>>t;
    while(t--){
        cin>>str>>k;
        int len=strlen(str);
        for(int i=0;i<len;i++){
            if(str[i]=='A')s[i]=0;
            if(str[i]=='T')s[i]=1;
            if(str[i]=='C')s[i]=2;
            if(str[i]=='G')s[i]=3;
            d[i]=i;
        }
        int x=len-k;
        memset(f,0,sizeof(f));
        memset(b,0,sizeof(b));
        for(int i=0;i<k;i++){
            d[i]=min(d[i],d[x+i]);
            d[i+x]=d[i];
            if(!b[i])f[d[i]][s[i]]++;b[i]=1;
            if(!b[i+x])f[d[i]][s[i+x]]++;b[i+x]=1;
        }
        int ans=0;

        for(int i=0;i<k;i++){
            x=0;
            int y=0;
            for(int j=0;j<4;j++){x+=f[i][j];y=max(y,f[i][j]);}
            ans+=x-y;
        }
        cout<<ans<<endl;
    }
    return 0;
}