【poj2774】 Long Long Message

// poj2774
#include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<cmath>
#define LL long long
#define inf 2147483640
#define Pi acos(-1.0)
#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);
using namespace std;

const int maxn=1000010;
char s[maxn],s1[maxn];
int wa[maxn],wb[maxn],w[maxn],wv[maxn],sa[maxn],rank[maxn],height[maxn];

bool cmp(int *r,int a,int b,int l) {return r[a]==r[b] && r[a+l]==r[b+l];}
void da(char *r,int *sa,int n,int m) {
    int i,j,p,*x=wa,*y=wb,*t;
    for (i=0;i<m;i++) w[i]=0;
    for (i=0;i<n;i++) w[x[i]=r[i]]++;
    for (i=1;i<m;i++) w[i]+=w[i-1];
    for (i=n-1;i>=0;i--) sa[--w[x[i]]]=i;
    for (p=1,j=1;p<n;j*=2,m=p) {
        for (p=0,i=n-j;i<n;i++) y[p++]=i;
        for (i=0;i<n;i++) if (sa[i]>=j) y[p++]=sa[i]-j;
        for (i=0;i<n;i++) wv[i]=x[y[i]];
        for (i=0;i<m;i++) w[i]=0;
        for (i=0;i<n;i++) w[wv[i]]++;
        for (i=1;i<m;i++) w[i]+=w[i-1];
        for (i=n-1;i>=0;i--) sa[--w[wv[i]]]=y[i];
        for (p=1,t=x,x=y,y=t,x[sa[0]]=0,i=1;i<n;i++)
            x[sa[i]]=cmp(y,sa[i-1],sa[i],j)?p-1:p++;
    }
    sa[0]=0;
}
void calheight(char *r,int *sa,int n) {
    for (int i=1;i<=n;i++) rank[sa[i]]=i;
    int k=0;
    for (int i=0;i<n;height[rank[i++]]=k) {
        k?k--:0;
        for (int j=sa[rank[i]-1];r[i+k]==r[j+k];k++);
    }
}
int main() {
    //free("aaa");
    scanf("%s%s",s,s1);
    int n=strlen(s);
    int n1=strlen(s1);
    s[n++]=‘0‘;
    for (int i=0;i<n1;i++) s[n+i]=s1[i];
    int l=n-1;
    n+=n1;
    s[n]=‘#‘;
    da(s,sa,n+1,200);
    calheight(s,sa,n);
    int ans=0;
    for (int i=2;i<=n;i++)
        if ((sa[i-1]<l && sa[i]>l) || (sa[i-1]>l && sa[i]<l)) ans=max(ans,height[i]);
    printf("%d",ans);
    fclose(stdin);fclose(stdout);
    return 0;
}