DC3求后缀数组板子

#include<bits/stdc++.h>

#define LL long long

#define fi first

#define se second

#define mk make_pair

#define PLL pair<LL, LL>

#define PLI pair<LL, int>

#define PII pair<int, int>

#define SZ(x) ((int)x.size())

#define ull unsigned long long

using namespace std;

const int N = 2e6 + ;

const int inf = 0x3f3f3f3f;

const LL INF = 0x3f3f3f3f3f3f3f3f;

const int mod = ;

const double eps = 1e-;

const double PI = acos(-);

#define F(x) ((x) / 3 + ((x) % 3 == 1 ? 0 : tb))

#define G(x) ((x) < tb ? (x) * 3 + 1 : ((x) - tb) * 3 + 2)

int r[ * N], sa[ * N];

int wa[ * N], wb[ * N], wv[ * N], ss[ * N];

int rnk[N], lcp[N];

int c0(int *r, int a, int b) {return r[a] == r[b] && r[a + ] == r[b + ] && r[a + ] == r[b + ]; }

int c12(int k, int *r, int a, int b) {

    if(k == ) return r[a] < r[b] || r[a] == r[b] && c12(, r, a + , b + );

    return r[a] < r[b] || r[a] == r[b] && wv[a + ] < wv[b + ];

}

void sort(int *r, int *a, int *b, int n, int m) {

    for(int i = ; i < n; i++) wv[i] = r[a[i]];

    for(int i = ; i < m; i++) ss[i] = ;

    for(int i = ; i < n; i++) ss[wv[i]]++;

    for(int i = ; i < m; i++) ss[i] += ss[i - ];

    for(int i = n - ; i >= ; i--) b[--ss[wv[i]]] = a[i];

}

void DC3(int *r, int *sa, int n, int m) {

    int i, j, p;

    int *san = sa + n, *rn = r + n;

    int ta = , tb = (n + ) / , tbc = ;

    r[n] = r[n + ] = ;

    for(i = ; i < n; i++) if(i %  != ) wa[tbc++] = i;

    sort(r + , wa, wb, tbc, m);

    sort(r + , wb, wa, tbc, m);

    sort(r, wa, wb, tbc, m);

    for(p = , rn[F(wb[])] = , i = ; i < tbc; i++)

        rn[F(wb[i])] = c0(r, wb[i - ], wb[i]) ? p -  : p++;

    if(p < tbc) DC3(rn, san, tbc, p);

    else for(i = ; i < tbc; i++) san[rn[i]] = i;

    for(i = ; i < tbc; i++) if(san[i] < tb) wb[ta++] = san[i] * ;

    if(n %  == ) wb[ta++] = n - ;

    sort(r, wb, wa, ta, m);

    for(i = ; i < tbc; i++) wv[wb[i] = G(san[i])] = i;

    for(i = , j = , p = ; i < ta && j < tbc; p++)

        sa[p] = c12(wb[j] % , r, wa[i], wb[j]) ? wa[i++] : wb[j++];

    for( ; i < ta; p++) sa[p] = wa[i++];

    for( ; j < tbc; p++) sa[p] = wb[j++];

}

void calc_LCP(int *r, int *sa, int n) {

    int k = ;

    for(int i = ; i < n; i++) rnk[sa[i]] = i;

    for(int i = ; i < n - ; lcp[rnk[i++]] = k) {

        if(k) k--;

        for(int j = sa[rnk[i] - ]; r[i + k] == r[j + k]; k++);

    }

}

int n, m, tot;

char S[N], T[N];

int main() {

    scanf("%s%s", S, T);

    n = strlen(S); m = strlen(T);

    for(int i = ; i < n; i++) r[tot++] = S[i];

    r[tot++] = '$';

    for(int i = ; i < m; i++) r[tot++] = T[i];

    DC3(r, sa, tot + , );

    calc_LCP(r, sa, tot + );

    return ;

}

/*

*/