HDU 1403 Longest Common Substring

好久没学新算法了，从现在开始努力吧。

花了3天时间看了后缀数组的论文，差不多看明白了，贴上一份应用的代码吧。

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>#include <vector>#include <map>#include <queue>#include <ctime>#include <set>#include <deque>#include <string>#define MP make_pair#define PB push_back#define SZ(x) ((int)(x).size())#define REP(i,n) for (int _n=n,i=0; (i)<_n; ++(i))#define FOR(i,a,b) for (int _b=b,i=(a);i<=_b;++(i))#define FOREACH(it,c) for ( __typeof((c).begin()) it=(c).begin(),ite=(c).end(); it!=ite; ++it )int rint() { int x; if(~scanf("%d",&x)) return x; return -1; }typedef long long LL;const int inf=~0U>>1;using namespace std;const int maxN=200010;const int maxC=300;int n,sa[maxN],height[maxN],top[maxN],rank[maxN],tmp[maxN],len1,ans;string s;void makesa(){memset(top,0,sizeof(top));REP(i,n) top[rank[i]=s[i]]++;for(int i=1;i<maxN;i++) top[i]+=top[i-1];REP(i,n) sa[--top[rank[i]]]=i;for(int len=1;len<n;len<<=1){int j=0;REP(i,n){j=sa[i]-len;if(j<0) j+=n;tmp[top[rank[j]]++]=j;}sa[tmp[top[0]=0]]=j=0;for(int i=1;i<n;i++){if(rank[tmp[i]]!=rank[tmp[i-1]]||rank[tmp[i]+len]!=rank[tmp[i-1]+len])top[++j]=i;sa[tmp[i]]=j;}memcpy(rank,sa,n*sizeof(int));memcpy(sa,tmp,n*sizeof(int));if(j>=n-1) return;}}void calheight(){int i,j,k;for(j=rank[height[i=k=0]=0];i<n-1;i++,k++){while(k>=0&&s[i]!=s[sa[j-1]+k]){height[j]=(k--);if((sa[j]<len1&&sa[j-1]>len1)||(sa[j]>len1&&sa[j-1]<len1)) {//puts("**");if(ans<height[j]) ans=height[j];}j=rank[sa[j]+1];}}}int main(){#ifndef ONLINE_JUDGE    freopen("a.in","r",stdin);    freopen("a.out","w",stdout);#endifstring s1,s2;while(cin>>s1>>s2){len1=SZ(s1);s=s1+"$"+s2;n=s.size()+1;ans=0;makesa();calheight();cout<<ans<<endl;}return 0;}