poj 3261

       给出n个数字的序列，求其中出现了k次的最长可重叠公共子串。典型的后缀数组模板题，直接上代码了。

#include <cstdio>
#include <stack>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <list>
#include <functional>
#include <cstring>
#include <algorithm>
#include <cctype>
#include <string>
#include <map>
#include <iomanip>
#include <cmath>
#define LL long long
#define ULL unsigned long long
#define SZ(x) (int)x.size()
#define MP(a, b) make_pair(a, b)
#define MS(arr, num) memset(arr, num, sizeof(arr))
#define PB push_back
#define F first
#define S second
#define ROP freopen("input.txt", "r", stdin);
#define MID(a, b) (a + ((b - a) >> 1))
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define lrt rt << 1
#define rrt rt << 1|1
#define root 1,n,1
#define BitCount(x) __builtin_popcount(x)
#define BitCountll(x) __builtin_popcountll(x)
#define LeftPos(x) 32 - __builtin_clz(x) - 1
#define LeftPosll(x) 64 - __builtin_clzll(x) - 1
const double PI = acos(-1.0);
const int INF = 1e7;
using namespace std;
const double eps = 1e-5;
const int MAXN = 300 + 10;
const int MOD = 1000007;
const double M=1e-8;
const int N=int(2e5)+10;
typedef pair<int, int> pii;
typedef pair<int, string> pis;
int m,sa[N],rank[N],height[N];
int wa[N],wb[N],wv[N], cnt[N];
bool cmp(int *y,int a,int b,int l)
{
    return y[a]==y[b] && y[a+l]==y[b+l];
}
void da(int s[],int n,int m)
{
    int i,j,p,*x=wa,*y=wb;
    MS(cnt,0);
    for (i=0;i<n;i++) cnt[x[i]=s[i]]++;
    for (i=1;i<m;i++) cnt[i]+=cnt[i-1];
    for (i=n-1;i>=0;i--) sa[--cnt[x[i]]]=i;
    for (j=1,p=1;p<n;j<<=1,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]];
        MS(cnt,0);
        for (i=0;i<n;i++) cnt[wv[i]]++;
        for (i=1;i<m;i++) cnt[i]+=cnt[i-1];
        for (i=n-1;i>=0;i--) sa[--cnt[wv[i]]]=y[i];
        swap(x,y);
        for (i=1,p=1,x[sa[0]]=0;i<n;i++) {
            x[sa[i]]=cmp(y,sa[i],sa[i-1],j)?p-1:p++;
        }
    }
}
void getHeight(int s[],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];s[i+k]==s[j+k];k++) ;
    }
}
vector<int> v[N];
bool check(int k,int n)
{
    int i,j,cur=-1;
    if (k==0) return true;
    for (i=1;i<=n;i++) {
        if (height[i]<k) v[++cur].clear();
        v[cur].push_back(i);
    }
    for (i=0;i<=cur;i++) {
        if (v[i].size()>=m) return true;
    }
    return false;
}
int slove(int n)
{
    int l=1,r=n,ans=0;
    while(l<=r) {
        int mid=MID(l,r);
        if (check(mid,n)) ans=mid,l=mid+1;
        else r=mid-1;
    }
    return ans;
}
int s[N];
int main()
{
    int i,j,k,n;
    while(~scanf("%d%d",&n,&m))
    {
        int mx=-INF;
        for (i=0;i<n;i++) scanf("%d",s+i),s[i]++,mx=max(mx,s[i]);
        s[n]=0;
        da(s,n+1,mx+1);
        getHeight(s,n);
//        for (i=1;i<=n;i++) cout<<sa[i]<<" "; cout<<endl;
//        for (i=0;i<n;i++) cout<<rank[i]<<" "; cout<<endl;
//        for (i=1;i<=n;i++) cout<<height[i]<<" "; cout<<endl;
        printf("%d\n",slove(n));
    }
}

/*
5 2
1 2 3 2 3

*/