Codeforces Round #294 (Div. 2) D. A and B and Interesting Substrings [dp 前缀和 ]

骑猪看日落 2021-12-23 10:27 201阅读 0赞

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D. A and B and Interesting Substrings

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

A and B are preparing themselves for programming contests.

After several years of doing sports programming and solving many problems that require calculating all sorts of abstract objects, A and B also developed rather peculiar tastes.

A likes lowercase letters of the Latin alphabet. He has assigned to each letter a number that shows how much he likes that letter (he has assigned negative numbers to the letters he dislikes).

B likes substrings. He especially likes the ones that start and end with the same letter (their length must exceed one).

Also, A and B have a string *s*. Now they are trying to find out how many substrings *t* of a string *s* are interesting to B (that is, *t* starts and ends with the same letter and its length is larger than one), and also the sum of values of all letters (assigned by A), except for the first and the last one is equal to zero.

Naturally, A and B have quickly found the number of substrings *t* that are interesting to them. Can you do it?

Input

The first line contains 26 integers *x**a*, *x**b*, ..., *x**z* ( - 105 ≤ *x**i* ≤ 105) — the value assigned to letters *a*, *b*, *c*, ..., *z* respectively.

The second line contains string *s* of length between 1 and 105 characters, consisting of Lating lowercase letters— the string for which you need to calculate the answer.

Output

Print the answer to the problem.

Sample test(s)

Input

1 1 -1 1 1 1 1 1 1 1 1 1 1 1 1 7 1 1 1 8 1 1 1 1 1 1
    xabcab

Output

Input

1 1 -1 1 1 1 1 1 1 1 1 1 1 1 1 7 1 1 1 8 1 1 1 1 1 1
    aaa

Output

Note

In the first sample test strings satisfying the condition above are *abca* and *bcab*.

In the second sample test strings satisfying the condition above are two occurences of *aa*.

没想到用前缀和，弱爆了

<table> 
 <tbody> 
  <tr> 
   <td><a title="Source" href="http://codeforces.com/contest/519/my" rel="nofollow">10091856</a></td> 
   <td>2015-03-01 08:23:44</td> 
   <td><a title="Candidate Master njczy2010" href="http://codeforces.com/profile/njczy2010" rel="nofollow">njczy2010</a></td> 
   <td><a href="http://codeforces.com/contest/519/problem/D" rel="nofollow"> D - A and B and Interesting Substrings </a></td> 
   <td>GNU C++</td> 
   <td><span>Accepted</span></td> 
   <td>62 ms</td> 
   <td>7976 KB</td> 
  </tr> 
  <tr> 
   <td><a title="Source" href="http://codeforces.com/contest/519/my" rel="nofollow">10090622</a></td> 
   <td>2015-03-01 04:45:07</td> 
   <td><a title="Candidate Master njczy2010" href="http://codeforces.com/profile/njczy2010" rel="nofollow">njczy2010</a></td> 
   <td><a href="http://codeforces.com/contest/519/problem/D" rel="nofollow"> D - A and B and Interesting Substrings </a></td> 
   <td>GNU C++</td> 
   <td><span><span>Time limit exceeded on test <span>6 </span></span></span></td> 
   <td>2000&nbsp;ms</td> 
   <td>12200&nbsp;KB</td> 
  </tr> 
 </tbody> 
</table>

1 #include<iostream>
     2 #include<cstring>
     3 #include<cstdlib>
     4 #include<cstdio>
     5 #include<algorithm>
     6 #include<cmath>
     7 #include<queue>
     8 #include<map>
     9 #include<set>
    10 #include<stack>
    11 #include<string>
    12 
    13 #define N 100005
    14 #define M 10005
    15 #define mod 1000000007
    16 //#define p 10000007
    17 #define mod2 1000000000
    18 #define ll long long
    19 #define ull unsigned long long
    20 #define LL long long
    21 #define eps 1e-6
    22 //#define inf 2147483647
    23 #define maxi(a,b) (a)>(b)? (a) : (b)
    24 #define mini(a,b) (a)<(b)? (a) : (b)
    25 
    26 using namespace std;
    27 
    28 ll a[30];
    29 char s[N];
    30 int l;
    31 ll ans;
    32 map<ll,ll>mp[30];
    33 ll sum;
    34 
    35 void ini()
    36 {
    37     ans=0;
    38     int i;
    39     int te;
    40     for(i=1;i<26;i++){
    41         scanf("%I64d",&a[i]);
    42     }
    43     for(i=0;i<26;i++){
    44         mp[i].clear();
    45     }
    46     scanf("%s",s);
    47     l=strlen(s);
    48     sum=0;
    49     for(i=0;i<l;i++){
    50         te=s[i]-'a';
    51         ans+=mp[te][sum];
    52         sum+=a[te];
    53         mp[te][sum]++;
    54     }
    55 }
    56 
    57 void solve()
    58 {
    59 
    60 }
    61 
    62 void out()
    63 {
    64     printf("%I64d\n",ans);
    65 }
    66 
    67 int main()
    68 {
    69     //freopen("data.in","r",stdin);
    70     //freopen("data.out","w",stdout);
    71     //scanf("%d",&T);
    72     //for(int ccnt=1;ccnt<=T;ccnt++)
    73     //while(T--)
    74     //scanf("%d%d",&n,&m);
    75     while(scanf("%I64d",&a[0])!=EOF)
    76     {
    77         ini();
    78         solve();
    79         out();
    80     }
    81     return 0;
    82 }

转载于:https://www.cnblogs.com/njczy2010/p/4306972.html

[Link 1]: http://codeforces.com/contest/519/problem/D