POJ 2774（后缀数组）

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(http://acm.hust.edu.cn/vjudge/contest/view.action?cid=105595#problem/I)
题意：寻找字符串A,B的最长相同子串
解法：构造个后缀数组，随便搞一搞就好了。感觉用Hash+二分也该也能做，太懒了不想了。。。

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#include <cmath>#include <vector>#include <queue>#include <stack>#include <set>#include <map>#include <queue>//#include <tr1/unordered_set>//#include <tr1/unordered_map>#include <bitset>//#pragma comment(linker, "/STACK:1024000000,1024000000")using namespace std;#define lson l, m, rt<<1#define rson m+1, r, rt<<1|1#define inf 1e9#define debug(a) cout << #a" = " << (a) << endl;#define debugarry(a, n) for (int i = 0; i < (n); i++) { cout << #a"[" << i << "] = " << (a)[i] << endl; }#define clr(x, y) memset(x, y, sizeof x)#define ll long long#define ull unsigned long long#define FOR(i,a,b) \    for(i=a;a<b?i<=b:i>=b;a<b?i++:i--)const int maxn = 100000*2*2+100;struct suffix_array{    char s[maxn];    int sa[maxn],t[maxn],t2[maxn],c[maxn];    int n;    void build_sa(int m)    {        int i,*x=t,*y=t2;        FOR(i,0,m-1) c[i]=0;        FOR(i,0,n-1) c[x[i]=s[i]]++;        FOR(i,1,m-1) c[i]+=c[i-1];        FOR(i,n-1,0) sa[--c[x[i]]]=i;        for(int k=1;k<=n;k<<=1){            int p=0;            FOR(i,n-k,n-1) y[p++]=i;            FOR(i,0,n-1) if(sa[i]>=k) y[p++]=sa[i]-k;            FOR(i,0,m-1) c[i]=0;            FOR(i,0,n-1) c[x[y[i]]]++;            FOR(i,0,m-1) c[i]+=c[i-1];            FOR(i,n-1,0) sa[--c[x[y[i]]]]=y[i];            swap(x,y);            p=1;            x[sa[0]]=0;            FOR(i,1,n-1)                x[sa[i]]=y[sa[i-1]]==y[sa[i]]&&                y[sa[i-1]+k]==y[sa[i]+k]?p-1:p++;            if(p>=n) break;            m=p;        }    }    int Rank[maxn],height[maxn];    void getHeight()    {        int k=0;        for(int i=0;i<n;i++) Rank[sa[i]]=i;        for(int i=0;i<n;i++){            if(k) k--;            int j=sa[Rank[i]-1];            while(s[i+k]==s[j+k]) k++;            height[Rank[i]]=k;        }    }}su;char s[maxn],s2[maxn];int main(){    //freopen("input.txt","r",stdin);    while(~scanf("%s%s",s,s2))    {        int len=strlen(s);        strcat(s,"&");        strcat(s,s2);        strcpy(su.s,s);        su.n=strlen(s)+1;        su.build_sa(255);        su.getHeight();        int ans=0,last1=0,last2=0;        for(int i=1;i<=su.n;i++)        {            if( su.sa[i] <= len )            {                last1 = inf;                last2 = min(last2,su.height[i]);                ans = max( ans , last2);            }            else            {                last2 = inf;                last1 = min(last1,su.height[i]);                ans = max( ans , last1);            }        }        printf("%d\n",ans);    }    return 0;}

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