SPOJ - PHRASES Relevant Phrases of Annihilation （后缀数组）

#include<iostream>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<ctime>

#define fuck(x) cerr<<#x<<" = "<<x<<endl;
#define debug(a, x) cerr<<#a<<"["<<x<<"] = "<<a[x]<<endl;
#define ls (t<<1)
#define rs ((t<<1)|1)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
const int maxn = 100186;
const int maxm = 100086;
const int inf = 0x3f3f3f3f;
const ll Inf = 999999999999999999;
const int mod = 1000000007;
const double eps = 1e-6;
const double pi = acos(-1);

int s[maxn];
int len, Rank[maxn], sa[maxn], tlen, tmp[maxn];

bool compare_sa(int i, int j) {
    if (Rank[i] != Rank[j]) { return Rank[i] < Rank[j]; }
    //如果以i开始,长度为k的字符串的长度,已经超出了字符串尾,那么就赋值为-1
    //这是因为,在前面所有数据相同的情况下,字符串短的字典序小.
    int ri = i + tlen <= len ? Rank[i + tlen] : -inf;
    int rj = j + tlen <= len ? Rank[j + tlen] : -inf;
    return ri < rj;
}

void construct_sa() {
    //初始的RANK为字符的ASCII码
    for (int i = 0; i <= len; i++) {
        sa[i] = i;
        Rank[i] = i < len ? s[i] : -inf;
    }
    for (tlen = 1; tlen <= len; tlen *= 2) {
        sort(sa, sa + len + 1, compare_sa);
        tmp[sa[0]] = 0;
        //全新版本的RANK,tmp用来计算新的rank
        //将字典序最小的后缀rank计为0
        //sa之中表示的后缀都是有序的,所以将下一个后缀与前一个后缀比较,如果大于前一个后缀,rank就比前一个加一.
        //否则就和前一个相等.
        for (int i = 1; i <= len; i++) {
            tmp[sa[i]] = tmp[sa[i - 1]] + (compare_sa(sa[i - 1], sa[i]) ? 1 : 0);
        }
        for (int i = 0; i <= len; i++) {
            Rank[i] = tmp[i];

        }
    }
}

int height[maxn];

void construct_lcp() {
//    for(int i=0;i<=n;i++){Rank[sa[i]]=i;}
    int h = 0;
    height[0] = 0;
    for (int i = 0; i < len; i++) {//i为后缀数组起始位置
        int j = sa[Rank[i] - 1];//获取当前后缀的前一个后缀(排序后)
        if (h > 0)h--;
        for (; j + h < len && i + h < len; h++) {
            if (s[j + h] != s[i + h])break;
        }
        height[Rank[i]] = h;
    }
}

int st[maxn][20];

void rmq_init() {
    for (int i = 1; i <= len; i++) {
        st[i][0] = height[i];
    }
    int l = 2;
    for (int i = 1; l <= len; i++) {
        for (int j = 1; j + l / 2 <= len; j++) {
            st[j][i] = min(st[j][i - 1], st[j + l / 2][i - 1]);
        }
        l <<= 1;
    }
}

int ask_min(int i, int j) {
    int k = int(log(j - i + 1.0) / log(2.0));
    return min(st[i][k], st[j - (1 << k) + 1][k]);
}

int lcp(int a, int b)//此处参数是,原字符串下标
{
    a = Rank[a], b = Rank[b];
    if (a > b)
        swap(a, b);
    return ask_min(a + 1, b);
}


char str[maxn];
int intr[maxn];
int mx[105];
int mn[105];
int n;
bool check(int mid){
    if(mid==0){ return  true;}
    memset(mx,0,sizeof(mn));
    memset(mn,0x3f,sizeof(mn));
    for(int i=1;i<=len;i++){
        int prestart =  lower_bound(intr+1,intr+1+n,sa[i-1])-intr;
        int start = lower_bound(intr+1,intr+1+n,sa[i])-intr;
//        cout<<height[i]<<endl;
        if(height[i]>=mid){
            mn[start]=min(mn[start],sa[i]);
            mx[start]=max(mx[start],sa[i]);
            mn[prestart]=min(mn[prestart],sa[i-1]);
            mx[prestart]=max(mx[prestart],sa[i-1]);
        }else{
            bool flag=true;
//            fuck(n)
            for(int j=1;j<=n;j++){
//                cerr<<mx[j]<<" "<<mn[j]<<endl;
                if(mx[j]-mn[j]<mid){flag=false;}
            }
            if(flag){return true;}
            memset(mx,0,sizeof(mn));
            memset(mn,0x3f,sizeof(mn));
        }
    }
    return false;
}

int main() {
//    ios::sync_with_stdio(false);
//    freopen("in.txt", "r", stdin);

    int cases=0;

    int T;
    scanf("%d",&T);
    while (T--){
        scanf("%d",&n);
        cases++;
        len=0;
        int lenx = 0;
        for(int i=1;i<=n;i++){
            scanf("%s",str);
            int l=strlen(str);
            lenx = max(lenx,l);
            for(int j=0;j<l;j++){
                s[len++]=(int)str[j]-‘a‘+1;
            }
            s[len++]=200+i;
            intr[i]=len-1;
        }


        construct_sa();
        construct_lcp();


//        fuck(check(4));
        int l=0,r=lenx;
        int ans=0;
        while (r>=l){
            int mid=(l+r)/2;
//            cout<<mid<<endl;
//            cout<<l<<" "<<r<<endl;
            if(check(mid)){
                ans=mid;
                l=mid+1;
            }else{
                r=mid-1;
            }
        }
        printf("%d\n",ans);
    }

    return 0;
}