poj 1743 - c++编程基础 - 编程开发网

后缀数组

[cpp]
#include
#include
#include
using namespace std;
#define MAXN 20010
int n,r[20010];
int sa[20010];
int wa[MAXN],wb[MAXN],wv[MAXN],ws[MAXN];
int height[MAXN],rank[MAXN];
inline bool cmp(int *r,int a,int b,int len){
return r[a]==r[b]&&r[a+len]==r[b+len];
}
void SA(int n,int m){
int i,j,p,*x=wa,*y=wb,*t;
for(i=0;i ws[i]=0;
for(i=0;i ws[x[i]=r[i]]++;
for(i=1;i ws[i]+=ws[i-1];
for(i=n-1;i>=0;i--)
sa[--ws[x[i]]]=i;
for(j=p=1;p for(p=0,i=n-j;i y[p++]=i;
for(i=0;i if(sa[i]>=j)
y[p++]=sa[i]-j;
}
for(i=0;i ws[i]=0;
for(i=0;i ws[wv[i]=x[y[i]]]++;
for(i=1;i ws[i]+=ws[i-1];
for(i=n-1;i>=0;i--)
sa[--ws[wv[i]]]=y[i];
for(t=x,x=y,y=t,x[sa[0]]=0,p=i=1;i x[sa[i]]=cmp(y,sa[i-1],sa[i],j) p-1:p++;
}
}
void Height(int n){
int i,j,k=0;
for(i=1;i<=n;i++) //注意sa[0]是以r[n-1]开始的串即0，所以这里忽略sa[0]。
rank[sa[i]]=i;
for(i=0;i

for(k k--:0,j=sa[rank[i]-1];r[i+k]==r[j+k];k++);
}
bool ok(int mid){
int i,maxk,mink;
maxk=mink=sa[1];
for(i=2;i if(height[i]>=mid){ //这里是>=
maxk=max(maxk,sa[i]);
mink=min(mink,sa[i]);
if(maxk-mink>mid) //注意这里要>
return 1;
}
else
maxk=mink=sa[i];
}
return 0;
}
int main(){
int i,j;
while(scanf("%d",&n)){
memset(height,0,sizeof(height));
if(n==0)break;
for(i=0;i scanf("%d",&r[i]);
for(i=0;i r[i]=r[i+1]-r[i]+88;
r[n-1]=0;
SA(n,177);
Height(n-1);
int high=n,low=4;
int ans=0;
while(low<=high){
int mid=(high+low)>>1;
if(ok(mid)){
ans=mid;
low=mid+1;
}
else
high=mid-1;
}
if(ans>=4)
printf("%d\n",ans+1);
else
printf("0\n");
}
}

作者：waitfor_