cogs1713 [POJ2774]很长的信息

cogs1713 [POJ2774]很长的信息

原题链接

题解

// It is made by XZZ
#include<cstdio>
#include<algorithm>
#include<cstring>
#define Fname "lcs"
using namespace std;
#define rep(a,b,c) for(rg int a=b;a<=c;a++)
#define drep(a,b,c) for(rg int a=b;a>=c;a--)
#define erep(a,b) for(rg int a=fir[b];a;a=nxt[a])
#define il inline
#define rg register
#define vd void
typedef long long ll;
il int gi(){
rg int x=0;rg char ch=getchar();
while(ch<'0'||ch>'9')ch=getchar();
while(ch>='0'&&ch<='9')x=x*10+ch-'0',ch=getchar();
return x;
}
const int maxn=1200010;
char A[maxn],B[maxn];
int a,b;
int n,s[maxn],m;
int sa[maxn],rk[maxn],tmp[maxn],buc[maxn],ht[maxn];
il vd Qsort(){
rep(i,0,m)buc[i]=0;
rep(i,1,n)buc[rk[tmp[i]]]++;
rep(i,1,m)buc[i]+=buc[i-1];
drep(i,n,1)sa[buc[rk[tmp[i]]]--]=tmp[i];
}
il bool cmp(int*h,int a,int b,int l){return h[a]==h[b]&&h[a+l]==h[b+l];}
il vd solve(){
m=127;
rep(i,1,n)rk[i]=s[i],tmp[i]=i;
Qsort();
int p=0;
for(rg int l=1;p<n;l<<=1){
p=0;
rep(i,n-l+1,n)tmp[++p]=i;
rep(i,1,n)if(sa[i]>l)tmp[++p]=sa[i]-l;
Qsort();
rep(i,1,n)tmp[i]=rk[i];
p=rk[sa[1]]=1;
rep(i,2,n)
if(cmp(tmp,sa[i],sa[i-1],l))rk[sa[i]]=p;
else rk[sa[i]]=++p;
m=p;
}
p=0;
rep(i,1,n)sa[rk[i]]=i;
rep(i,1,n){
if(p)--p;
if(rk[i]==n)continue;
while(s[i+p]==s[sa[rk[i]+1]+p])++p;
ht[rk[i]]=p;
}
}
il bool check(int&x,int&y){
if(x<=a&&y>a+1)return 1;
if(y<=a&&x>a+1)return 1;
return 0;
}
int main(){
freopen(Fname".in","r",stdin);
freopen(Fname".out","w",stdout);
scanf("%s%s",A+1,B+1);
a=strlen(A+1),b=strlen(B+1);
rep(i,1,a)s[++n]=A[i];
s[++n]='%';
rep(i,1,b)s[++n]=B[i];
s[n+1]='$';
solve();
int ans=0;
rep(i,1,n-1)if(check(sa[i],sa[i+1]))ans=max(ans,ht[i]);
printf("%d\n",ans);
return 0;
}