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  • String Game

    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 ta1... 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.

    Example

    Input
    ababcba
    abb
    5 3 4 1 7 6 2
    Output
    3
    Input
    bbbabb
    bb
    1 6 3 4 2 5
    Output
    4

    Note

    In the first sample test sequence of removing made by Nastya looks like this:

    "ababcba"  "ababcba"  "ababcba"  "ababcba"

    Nastya can not continue, because it is impossible to get word "abb" from word "ababcba".

    So, Nastya will remove only three letters.

    //大概意思就是给你个字符串,然后给你个比对的串,给你几个位置,依次从这几个位置删除第一个串中的字符,对比删除后字符2是否是字符1的子串,输出最多删除的次数。

    #include<bits/stdc++.h>
    using namespace std;
    
    char t[200010],p[200010];
    int flag[200010],a[200010],n,m;
    bool ceshi(int x);
    int main()
        {
            int l,r,mid;
            scanf("%s%s",t+1,p+1);
                n=strlen(t+1);
                m=strlen(p+1);
            for (int i=1;i<=n;i++)
                cin>>a[i];
            l=0,r=n; while (l<r)
            {
                mid=(l+r+1)/2;
                if (ceshi(mid)) l=mid;
                else r=mid-1;
                }
                cout<<l;
                }
    
    bool ceshi(int x) {
        int j=1;
        for (int i=1;i<=x;i++)
            flag[a[i]]=0;
        for (int i=x+1;i<=n;i++)
            flag[a[i]]=1;
        for (int i=1;i<=n&&j<=m;i++)
            if (flag[i]&&t[i]==p[j]) j++;
        return j==m+1;
        }
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  • 原文地址:https://www.cnblogs.com/upstart/p/6558638.html
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