hdu----(5056)Boring count(贪心)

Boring count

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 228    Accepted Submission(s): 90

Problem Description

You
are given a string S consisting of lowercase letters, and your task is
counting the number of substring that the number of each lowercase
letter in the substring is no more than K.

 

Input

In the first line there is an integer T , indicates the number of test cases.
For each case, the first line contains a string which only consist of lowercase letters. The second line contains an integer K.

[Technical Specification]
1<=T<= 100
1 <= the length of S <= 100000
1 <= K <= 100000

 

Output

For each case, output a line contains the answer.

 

Sample Input

3
abc
1
abcabc
1
abcabc
2

 

Sample Output

6
15
21

 

Source

BestCoder Round #11 (Div. 2)

 

   之前用一种动态规划式方法怎么用怎么TLE ，看了一下解题报告，发现有O(n)算法。觉得很是强大，........哎，还是太弱哇...╮(╯▽╰)╭

代码：

 #include<cstdio>
 #include<cstring>
 #include<iostream>
 using namespace std;
 const int maxn=;
 char str[maxn];
 int  sac[];
 int main()
 {
   int cas,st,pos,k;
   scanf("%d",&cas);
   while(cas--)
   {
       memset(sac,,sizeof(sac));
       scanf("%s %d",str,&k);
       __int64 ans=;
        st=;
       for(int i=;str[i]!='\0';i++)
     {
         pos=str[i]-'a';
         sac[pos]++;
         if(sac[pos]>k)
         {
             while(str[st]!=str[i])
             {
                 sac[str[st]-'a']--;
                 st++;
             }
             sac[str[st]-'a']--;
                 st++;
         }
         ans+=(i-st+);
     }
     printf("%I64d\n",ans);
   }
  return ;
 }