POJ 3691 DNA repair

#include<cstdio>
#include<cstring>
#include<iostream>
#include<iomanip>
#include<queue>
#include<cmath>
#include<stack>
#include<map>
#include<vector>
#include<set>
#include<algorithm>
using namespace std;
int n,sz;
int ch[1100][4],f[1100],val[1100],last[1100],dp[1050][1050];
int zhuanhuan (char c){
if(c=='A') return 0;
if(c=='C') return 1;
if(c=='G') return 2;
if(c=='T') return 3;
return 4;
}
void insert (char* c){
int i = 0;
int len = strlen(c);
for(int j = 0; j < len; j++){
int u = zhuanhuan(c[j]);
if(!ch[i][u]){
memset(ch[sz], 0, sizeof(ch[sz]));
ch[i][u] = sz;
sz++;
}
i = ch[i][u];
}
val[i] = 1;
}
void fail (){
queue<int> q;
for(int i = 0; i < 4; i++){
if(ch[0][i]){
q.push(ch[0][i]);
f[ch[0][i]] = 0;
}
}
while(!q.empty()){
int u = q.front();
q.pop();
for(int i = 0; i < 4; i++){
if(ch[u][i]){
int t = ch[u][i];
int p = f[u];
while(p && !ch[p][i]) p = f[p];
f[t] =ch[p][i];
last[t] = (val[f[t]] ? f[t] : last[f[t]]);
q.push(t);
}
}
}
}
void init(){
sz = 1;
memset(ch[0], 0, sizeof(ch[0]));
memset(f, 0, sizeof(f));
memset(last, 0, sizeof(last));
memset(val, 0, sizeof(val));
for(int i = 0; i < n; i++){
char c[25];
scanf("%s", c);
insert(c);
}
}
int main(int argc, const char * argv[])
{
int num = 1;
while(scanf("%d", &n)!=EOF){
if(n==0) break;
init();
fail();
char cs[1050];
scanf("%s", cs);
memset(dp, -1, sizeof(dp));
dp[0][0] = 0;
int len = strlen(cs);
for(int i = 0; i < len; i++){
for(int j = 0; j < sz; j++){
if(dp[i][j]!=-1){
int u = zhuanhuan(cs[i]);
for(int k = 0; k < 4; k++){
int jj;
if(ch[j][k]) jj = ch[j][k];
else{
int p = f[j];
while(p && !ch[p][k]) p = f[p];
jj = ch[p][k];
}
if(val[jj] || last[jj]!=0) continue;
if(k==u){
dp[i+1][jj] = (dp[i+1][jj]==-1 || dp[i+1][jj]>dp[i][j] ? dp[i][j] : dp[i+1][jj]);
}else{
dp[i+1][jj] = (dp[i+1][jj]==-1 || dp[i+1][jj]>dp[i][j]+1 ? dp[i][j]+1 : dp[i+1][jj]);
}
}
}
}
}
int ans = -1;
for(int i = 0; i < sz; i++){
if(dp[len][i] != -1){
if(ans==-1) ans = dp[len][i];
else ans = (ans > dp[len][i] ? dp[len][i] : ans);
}
}
printf("Case %d: %d\n", num++, ans);
}
}