hdu_2328_Corporate Identity(暴力枚举子串+KMP)

 1 #include<cstdio>
 2 #include<cstring>
 3 #define F(i,a,b) for(int i=a;i<=b;i++)
 4     
 5 const int N=210;
 6 int nxt[N],n,lens[4001],ans,l,r,cnt;
 7 char dt[4001][N];
 8 
 9 int KMP(int n,char*a,int m,char*b){
10     int i,j;
11     for(nxt[0]=j=-1,i=1;i<n;nxt[i++]=j){
12         while(~j&&a[j+1]!=a[i])j=nxt[j];
13         if(a[j+1]==a[i])j++;
14     }
15     for(j=-1,i=0;i<m;i++){
16         while(~j&&a[j+1]!=b[i])j=nxt[j];
17         if(a[j+1]==b[i])j++;
18         if(j==n-1)return 1;
19     }
20     return 0;
21 }
22 
23 inline void up(int &a,int b){if(a<b)a=b;}
24 inline void update(int L,int R){
25     if(R-L+1>ans)l=L,r=R,ans=r-l+1;
26     else if(R-L+1==ans)
27     {
28         for(int i=l,j=L;1;i++,j++){
29             if(dt[1][i]!=dt[1][j]){
30                 if(dt[1][i]<dt[1][j])return;
31                 else{
32                     l=L,r=R;
33                     return;
34                 }
35             }
36             if(i==r)return;
37             if(j==R)l=L,r=R;
38         }
39     }
40 }
41 
42 int main(){
43     while(~scanf("%d",&n),n)
44     {
45         F(i,1,n)scanf("%s",dt[i]),lens[i]=strlen(dt[i]);
46         char tp[201];
47         ans=-1,l=0,r=0,cnt=0;
48         F(i,0,lens[1]-1)F(j,i+cnt,lens[1]-1)
49         {
50             
51             int ed=0,fg=1;
52             F(ii,i,j)tp[ed++]=dt[1][ii];
53             F(ii,2,n)if(KMP(j-i+1,tp,lens[ii],dt[ii])==0){fg=0;break;}
54             if(fg)update(i,j),cnt=ans<1?0:ans-1;//剪枝，每次只找大于ans的
55         }
56         if(ans==-1)puts("IDENTITY LOST");
57         else {F(i,l,r)printf("%c",dt[1][i]);puts("");}
58     }
59     return 0;
60 }