Codeforces 779D - String Game

 

time limit per test
2 seconds
memory limit per test
512 megabytes
input
standard input
output
standard output

Little Nastya has a hobby, she likes to remove some letters from word, to obtain another word. But it turns out to be pretty hard for her, because she is too young. Therefore, her brother Sergey always helps her.

Sergey gives Nastya the word t and wants to get the word p out of it. Nastya removes letters in a certain order (one after another, in this order strictly), which is specified by permutation of letters' indices of the word t: a1... a|t|. We denote the length of word x as |x|. Note that after removing one letter, the indices of other letters don't change. For example, if t = "nastya" and a = [4, 1, 5, 3, 2, 6] then removals make the following sequence of words "nastya"  "nastya"  "nastya"  "nastya"  "nastya"  "nastya"  "nastya".

Sergey knows this permutation. His goal is to stop his sister at some point and continue removing by himself to get the word p. Since Nastya likes this activity, Sergey wants to stop her as late as possible. Your task is to determine, how many letters Nastya can remove before she will be stopped by Sergey.

It is guaranteed that the word p can be obtained by removing the letters from word t.

Input

The first and second lines of the input contain the words t and p, respectively. Words are composed of lowercase letters of the Latin alphabet (1 ≤ |p| < |t| ≤ 200 000). It is guaranteed that the word p can be obtained by removing the letters from word t.

Next line contains a permutation a1, a2, ..., a|t| of letter indices that specifies the order in which Nastya removes letters of t (1 ≤ ai ≤ |t|, all ai are distinct).

Output

Print a single integer number, the maximum number of letters that Nastya can remove.

Examples
input
ababcba
abb
5 3 4 1 7 6 2
output
3
input
bbbabb
bb
1 6 3 4 2 5
output
4
 1 #include<cstdio>
 2 #include<cstring>
 3 #include<iostream>
 4 using namespace std;
 5 int a[200000+5];
 6 char temp[200000+5];
 7 bool check(const char t[],const char p[],int mid)
 8 {
 9     memset(temp,0,sizeof(temp));
10     strcpy(temp,t); //拷贝到一个临时数组 
11     for(int i=1;i<=mid;i++) temp[a[i]-1]='0'; //把要划掉的那几个字母依次划掉
12     for(int i=0,j=0,temp_len=strlen(t),p_len=strlen(p);i<temp_len;i++){
13         if(temp[i] == p[j]) j++;
14         if(j == p_len) return true;
15     } 
16     return false;
17 }
18 int main()
19 {
20     char t[200000+5],p[200000+5];
21     scanf("%s%s",t,p);
22     int t_len=strlen(t);
23     for(int i=1;i<=t_len;i++) scanf("%d",&a[i]);
24     int st=0,ed=t_len;
25     while(ed-st>1)
26     {
27         int mid=st+(ed-st)/2;
28         if(check(t,p,mid)) st=mid;
29         else ed=mid;
30     }
31     printf("%d\n",st);
32 }

 

开始的时候一直在test 10上RUNTIME_ERROR，一直找不出原因，刚开始以为二分那边有问题，换了网上AC的二分方式依然是这样，后来才发现开int数组a[]的大小时候

200000+5写成了20000+5……真是僵硬……看来预定义一个MAXN不是没有道理的……


 

posted @ 2017-03-13 22:57  Dilthey  阅读(267)  评论(0)  编辑  收藏  举报