Poj 2774两个字符串的最长公共子串长度

#include<iostream>
#include<string.h>
#include<cstdio>
#include<cstring>
#define MIN(a,b) (a)>(b)?(b):(a)
#define MAX(a,b) (a)>(b)?(a):(b)
#define INF 0x3f3f3f
using namespace std;

const int M=200010;

int N,alen,blen;

int str[M];
char a[M>>1],b[M>>1];

int sa[M] , rank[M] , height[M];
int wa[M] , wb[M] , wv[M] , wd[M];

int cmp(int *r , int a , int b , int l)
{
return r[a] == r[b] && r[a+l] == r[b+l];
}

void da(int *r , int n , int m)
{
int i , j , p , *x = wa , *y = wb , *t;
for (i = 0 ; i < m ; i++)wd[i] = 0;
for (i = 0 ; i < n ; i++)wd[x[i]=r[i]]++;
for (i = 1 ; i < m ; i++)wd[i] += wd[i-1];
for (i = n-1 ; i >= 0 ; i--) sa[--wd[x[i]]] = i;
for (j = p = 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++)wd[i] = 0;
for (i = 0 ; i < n ; i++)wd[wv[i]]++;
for (i = 1 ; i < m ; i++)wd[i] += wd[i-1];
for (i = n-1 ; i >= 0 ; i--)sa[--wd[wv[i]]] = y[i];
for (t = x , x = y , y = t , p = 1 , x[sa[0]] = 0 , i  = 1 ; i < n ; i++)
x[sa[i]] = cmp(y,sa[i-1],sa[i],j)?p-1:p++;
}
}

void calheight(int *r , int n)
{
int i , j , k = 0;
for (i = 1 ; i <= n ; i++) rank[sa[i]] = i;
for (i = 0 ; i < n ; height[rank[i++]] = k)
for (k?k--:0,j = sa[rank[i]-1] ; r[i+k] == r[j+k] ; k++);  //若分割符为０则有可能会和Ｂ串末尾０配　导致ｈ多加１
}

int main()
{

int i,j;
memset(str,0,sizeof(str));
scanf("%s",a);
alen=strlen(a);
for(i=0;i<alen;i++)
str[i]=a[i]-'a'+2;  //保证为正数且比＇＄＇大
str[alen]=1;　//此处＇＄＇
scanf("%s",b);
blen=strlen(b);
for(i=alen+1,j=0;j<blen;j++,i++)
str[i]=b[j]-'a'+2;
int minlen=MIN(alen,blen);
int len=alen+blen;
da(str,len+1,30);
calheight(str,len);
int ans =0;
for (i =1; i <= len+1 ; i++)
if ((sa[i] < alen && sa[i -1] > alen) || (sa[i] > alen && sa[i -1] < alen))//保证一个在Ａ　一个在Ｂ
if (height[i] > ans)
ans = height[i];
printf("%d\n",ans);
return 0;
}