Simple DP with a vulnerability

Question Portal: http://acm.hust.edu.cn/vjudge/problem/viewProblem.action? Id = 18201

In fact, it is not difficult, but after a long time, I found that the original question was not clearly read, attention, the original sequence was too pitfall,

I have seen that many others use the longest common subsequence, but I use the longest ascending subsequence to map the original sequence to an ascending sequence, the data for this question exactly meets this condition.

For example, if the correct sequence is $5 \ 6 \ 4 \ 1 \ 3 \ 2 $, I can map it

$ Id [5] \ rightarrow 1 $ id [6] \ rightarrow 2 $ id [4] \ rightarrow 3 $

$ Id [1] \ rightarrow 4 $ id [3] \ rightarrow 5 $ id [2] \ rightarrow 6 $

For another sequence, such as $6 \ 1 \ 3 \ 2 \ 5 \ 4 $

Then I can map it to $2 \ 4 \ 5 \ 6 \ 1 \ 3 $ to find the longest ascending subsequence of the sequence.

Directly paste the Code:

#include <cstdio>#include <cstring>#include <iostream>using namespace std;const int maxn = 30;int ID[maxn];int b[maxn];int ans1,ans2;int a[maxn];int c[maxn];int n;int opt[maxn];int solve(){    int MAX = 0;    a[0] = -100;    memset(opt,0,sizeof(opt));    for(int i = 1;i <= n;++i)    for(int j = 0;j <= i-1;++j){        if(a[j] <= a[i])            opt[i] = max(opt[i],opt[j] + 1);    }    for(int i = 1;i <= n;++i){        MAX = max(MAX,opt[i]);    }    return MAX;}void print(){    for(int i = 1;i <= n;++i)        cout<<a[i]<<" ";    cout<<endl;}int getid(int index){    for(int i = 1;i <= n;++i)        if(ID[i] == index)        return i;}int main(){    //freopen("in.txt","r",stdin);    int fuck;    while(~scanf("%d",&n)){        for(int i = 1;i <= n;++i){            scanf("%d",&fuck);            ID[fuck] = i;        }        while(1){            ans1 = 0;            for(int i = 1;i <= n;++i){                if(scanf("%d",&fuck)==EOF) goto holly_shit;                a[fuck] = getid(i);            }            printf("%d\n",solve());            memset(a,0,sizeof(a));        }        holly_shit: continue;    }    return 0;}

Simple DP with a vulnerability