POJ1743 Musical Theme

  1 //It is made by jump~
  2 #include <iostream>
  3 #include <cstdlib>
  4 #include <cstring>
  5 #include <cstdio>
  6 #include <cmath>
  7 #include <algorithm>
  8 #include <ctime>
  9 #include <vector>
 10 #include <queue>
 11 #include <map>
 12 #include <set>
 13 #ifdef WIN32   
 14 #define OT "%I64d"
 15 #else
 16 #define OT "%lld"
 17 #endif
 18 using namespace std;
 19 typedef long long LL;
 20 const int MAXN = 20011;
 21 int ch[MAXN];
 22 int n,m;
 23 int wa[MAXN],wb[MAXN],c[MAXN];
 24 int rank[MAXN],height[MAXN];
 25 int sa[MAXN];
 26 int ans;
 27 
 28 inline int getint()
 29 {
 30     int w=0,q=0;
 31     char c=getchar();
 32     while((c<‘0‘ || c>‘9‘) && c!=‘-‘) c=getchar();
 33     if (c==‘-‘)  q=1, c=getchar();
 34     while (c>=‘0‘ && c<=‘9‘) w=w*10+c-‘0‘, c=getchar();
 35     return q ? -w : w;
 36 }
 37 
 38 inline void da(int m,int n){
 39     int i,*x=wa,*y=wb;
 40     for(i=1;i<=m;i++) c[i]=0;
 41     for(i=1;i<=n;i++) c[x[i]=ch[i]]++;
 42     for(i=1;i<=m;i++) c[i]+=c[i-1];
 43     for(i=n;i>=1;i--) sa[c[x[i]]--]=i;
 44     for(int k=1,p;k<=n;k=k*2) {
 45     p=0;
 46     for(i=n-k+1;i<=n;i++) y[++p]=i;
 47     for(i=1;i<=n;i++) if(sa[i]>k) y[++p]=sa[i]-k;
 48     for(i=1;i<=m;i++) c[i]=0;
 49     for(i=1;i<=n;i++) c[x[y[i]]]++;     
 50     for(i=1;i<=m;i++) c[i]+=c[i-1];
 51     for(i=n;i>=1;i--) sa[c[x[y[i]]]--]=y[i];
 52     swap(x,y);  x[sa[1]]=1; p=1;
 53     for(i=2;i<=n;i++) x[sa[i]]=(y[sa[i-1]]==y[sa[i]] && y[sa[i-1]+k]==y[sa[i]+k])?p:++p;
 54     if(p==n) break; m=p;
 55     }
 56 }
 57 
 58 inline void calheight(){
 59     int i,j,k=0;
 60     for(i=1;i<=n;i++) {
 61     if(k) k--;
 62     j=sa[rank[i]-1];
 63     while(ch[i+k]==ch[j+k]) k++;
 64     height[rank[i]]=k;//是rank[i]!!!
 65     }
 66 }
 67 
 68 inline bool check(int x){
 69     int i=2,minl,maxl;
 70     while(1) {
 71     while(i<=n && height[i]<x) i++;
 72     if(i>n) break;
 73     minl=maxl=sa[i-1];
 74     while(i<=n && height[i]>=x) minl=min(minl,sa[i]),maxl=max(maxl,sa[i]),i++;
 75     if(maxl-minl>x) return true;//不能等号！！！记录的是差
 76     }
 77     return false;
 78 }
 79 
 80 inline void work(){
 81     while(1) {
 82     n=getint();  if(n==0) break;
 83     memset(ch,0,sizeof(ch)); memset(sa,0,sizeof(sa));
 84     memset(wa,0,sizeof(wa)); memset(wb,0,sizeof(wb));
 85     memset(height,0,sizeof(height)); memset(rank,0,sizeof(rank));
 86     for(int i=1;i<=n;i++) ch[i]=getint();
 87     if(n<10) { printf("0\n"); continue; }
 88     for(int i=1;i<n;i++) ch[i]=ch[i+1]-ch[i],ch[i]+=89;
 89     ch[n]=0;
 90     da(300,n);
 91     for(int i=1;i<=n;i++) rank[sa[i]]=i;
 92     calheight();
 93     int l=1,r=n,mid; 
 94     while(l<r) {
 95         mid=(l+r)/2;
 96         if(check(mid)) l=mid+1;
 97         else r=mid;
 98     }
 99     if(l<=4) printf("0\n");
100     else printf("%d\n",l);
101     }
102 }
103 
104 int main()
105 {
106     work();
107     return 0;
108 }