经典双指针题型

#include <iostream>
using namespace std;

const int N = 200010;
char s[N];
int cnt[3];
int main()
{
    int m;
    cin >> m;
    while(m--)
    {
        cin >> s;
        int n = strlen(s);
        int res = n + 1;
        memset(cnt, 0, sizeof cnt);
        for(int i = 0 , j = 0 ; i < n ; i ++ ) 
        {
            cnt[s[i] - '1']++;
            while(cnt[s[j] - '1'] > 1)  
            {
                cnt[s[j] - '1']--;
                j++;
            }
            if(cnt[0] && cnt[1] && cnt[2] )
                {
                    res = min(res,i - j + 1);
                }

        }
        if(res == n + 1) res = 0;
        cout << res << endl;
    }
    return 0;
}