[KMP或者暴力]POJ 3450 Corporate Identity

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int MAXN = 222,MAXM = 4444;
char s[MAXM][MAXN],temp[MAXN],res[MAXN];
int next[MAXN],n;
void makenext(char *str){
int i = 0,j = -1,M = strlen(str);
next[0] = -1;
while(i<M){
if(str[i]==str[j]||j==-1)next[++i] = ++j;
else j = next[j];
}
}
int KMP(char *T,char *P){
int N = strlen(T),M = strlen(P),i = 0,j = 0;
while(i<N&&j<M){
if(T[i]==P[j]||j==-1)i++,j++;
else j = next[j];
}
return j==M?i-M:-1;
}
bool great(char *s1,char *s2){
int l1 = strlen(s1),l2 = strlen(s2);
if(l1!=l2)return l1>l2;
return strcmp(s1,s2)<0;
}
int main(){
while(scanf("%d",&n),n){
for(int i=0;i<n;i++)scanf("%s",s[i]);
int l = strlen(s[0]);res[0] = 0;
for(int i=0;i<l;i++){
for(int j=i;j<l;j++){
for(int k=0;k<j-i+1;k++){
temp[k] = s[0][k+i];
}
temp[j-i+1] = 0;
makenext(temp);
int ok = 1;
for(int k=1;k<n;k++){
if(KMP(s[k],temp)==-1){
ok = 0;break;
}
}
//cout<<temp<<" "<<ok<<endl;
if(ok&&great(temp,res)){
strcpy(res,temp);
}
}
}
if(res[0]){
printf("%s\n",res);
}else{
printf("IDENTITY LOST\n");
}
}
return 0;
}