String

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 892    Accepted Submission(s): 289


Problem Description There is a string S.S only contain lower case English character.(10≤length(S)≤1,000,000)
How many substrings there are that contain at least k(1≤k≤

26) distinct characters?
Input There are multiple test cases. The first line of input contains an integer T(1≤T≤10) indicating the number of test cases. For each test case:

The first line contains string S.
The second line contains a integer k(1≤k≤26).
Output For each test case, output the number of substrings that contain at least k

 dictinct characters.
Sample Input 2 abcabcabca 4 abcabcabcabc 3
Sample Output 0 55醉了，G++超時，C++過了。。。。AC-code：

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int main()
{
	int T,k,len,i,j,kk,vis[27];
	long long sum;
	char str[1000005];
	scanf("%d",&T);
	while(T--)
	{
		cin>>str;
		cin>>k;
		len=strlen(str);
		if(k==1)
		{
			cout<<(long long)(len+1)*len/2<<endl;
			continue;
		}
		kk=0;
		sum=0;
		memset(vis,0,sizeof(vis));
		j=0;
		for(i=0;i<len;i++)
		{
			if(!vis[str[i]-'a'])
				kk++;
			vis[str[i]-'a']++;
			while(kk>=k)
			{
				sum+=len-i;
				vis[str[j]-'a']--;
				if(!vis[str[j]-'a'])
				{
					kk--;
					j++;
					break;
				}
				j++;
			}
		}
		cout<<sum<<endl;
	}
	return 0;
 }