hdu 5672 String (尺取法)

String

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 1961    Accepted Submission(s): 636

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

2abcabcabca4abcabcabcabc3

 

Sample Output

055

 

Source

BestCoder Round #81 (div.2)

 

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#include<stdio.h>#include<algorithm>#include<string.h>using namespace std;char s[1000333];int c[30];int main(){    int T;    scanf("%d",&T);    while(T--)    {        scanf("%s",s);        memset(c,0,sizeof(c));        int len=strlen(s);        int l = 0,r = 0,k;        long long ans=0;        scanf("%d",&k);        int cnt=0;        while(l<=r&&l<len)        {            while(cnt<k&&r<len)            {                c[s[r]-'a']++;                if(c[s[r]-'a']==1)cnt++;                r++;            }            if(cnt==k)ans+=len-r+1;            if(c[s[l]-'a']==1)                cnt--;            c[s[l]-'a']--;            l++;        }        printf("%lld\n",ans);    }}