hdu 2457 DNA repair

          AC自动机+DP。按着自动机跑，（其实是生成新的满足题目要求的串，然后找改变最少的。）但是不能跑到是单词的地方，如果跑到单词的话那么说明改变后的串含有病毒了，不满足题意。然后就是应该怎么跑的问题了，现在我们从自动机的根节点开始跑，如果跑到下一个节点和当前串的字母不一样的话，那么当前位置生成的串是和原串在该位置是有差异的，dp+1，否者的话dp不变。所以dp[ i ][ j ]表示的是匹配到当前匹配串的位置时，跑到自动机的 j 节点需要改变的最少字母数。

#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstdlib>
#include <climits>
#include <cstring>
#include <cstdio>
#include <string>
#include <vector>
#include <cctype>
#include <queue>
#include <cmath>
#include <set>
#include <map>
#define CLR(a, b) memset(a, b, sizeof(a))
using namespace std;

const int MAX_NODE = 22 * 55 * 2;
const int INF = 0x3f3f3f3f;
const int CHILD_NUM = 4;
const int N = 1010;

class ACAutomaton
{
private:
int chd[MAX_NODE][CHILD_NUM];
int dp
[MAX_NODE];
int fail[MAX_NODE];
bool val[MAX_NODE];
int Q[MAX_NODE];
int ID[128];
int sz;
public:
void Initialize()
{
fail[0] = 0;
ID['A'] = 0;ID['G'] = 1;
ID['C'] = 2;ID['T'] = 3;
}
void Reset()
{
CLR(chd[0] , 0);sz = 1;
}
void Insert(char *a)
{
int p = 0;
for ( ; *a ; a ++)
{
int c = ID[*a];
if (!chd[p][c])
{
CLR(chd[sz] , 0);
val[sz] = false;
chd[p][c] = sz ++;
}
p = chd[p][c];
}
val[p] = true;
}
void Construct()
{
int *s = Q , *e = Q;
for (int i = 0 ; i < CHILD_NUM ; i ++)
{
if (chd[0][i])
{
fail[ chd[0][i] ] = 0;
*e ++ = chd[0][i];
}
}
while (s != e)
{
int u = *s++;
for (int i = 0 ; i < CHILD_NUM ; i ++)
{
int &v = chd[u][i];
if (v)
{
*e ++ = v;
fail[v] = chd[ fail[u] ][i];
val[v] |= val[fail[v]];
}
else
{
v = chd[ fail[u] ][i];
}
}
}
}
int Work(char *ch)
{
int len, S, T, ret;
len = strlen(ch);
CLR(dp, INF);dp[0][0] = 0;
for(int i = 0; i < len; i ++)
for(int j = 0; j < sz; j ++)
{
if(val[j]) continue;
if(dp[i][j] == INF) continue;
for(int k = 0; k < 4; k ++)
{
T = chd[j][k];
if(val[T]) continue;
dp[i + 1][T] = min(dp[i + 1][T], dp[i][j] + (ID[ch[i]] != k));
}
}ret = INF;
for(int i = 0; i < sz; i ++)
{
ret = min(ret, dp[len][i]);
}
return ret == INF ? -1 : ret;
}
} AC;

char ch
;

int main()
{
//freopen("input.txt", "r", stdin);
AC.Initialize();
int n, t, cas = 1;
while (scanf("%d", &n), n)
{
AC.Reset();
for (int i = 0 ; i < n ; i ++)
{
char temp[55];
scanf("%s", temp);
AC.Insert(temp);
}
scanf("%s", ch);
AC.Construct();
printf("Case %d: %d\n", cas ++, AC.Work(ch));
}
return 0;
}