后缀自动机

是什么？
博主不想写反正没人看
直接去\(hihocoder\)
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模板

# include <bits/stdc++.h>
# define IL inline
# define RG register
# define Fill(a, b) memset(a, b, sizeof(a))
using namespace std;
typedef long long ll;

template <class Int>
IL void Input(RG Int &x){
    RG int z = 1; RG char c = getchar(); x = 0;
    for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1;
    for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
    x *= z;
}

const int maxn(2e6 + 5);

int n, trans[26][maxn], fa[maxn], len[maxn], tot = 1, last = 1;
char s[maxn];

IL void Extend(RG int c){
    RG int np = ++tot, p = last; last = np;
    len[np] = len[p] + 1;
    while(p && !trans[c][p]) trans[c][p] = np, p = fa[p];
    if(!p) fa[np] = 1;
    else{
        RG int q = trans[c][p];
        if(len[p] + 1 == len[q]) fa[np] = q;
        else{
            RG int nq = ++tot;
            len[nq] = len[p] + 1, fa[nq] = fa[q];
            for(RG int i = 0; i < 26; ++i) trans[i][nq] = trans[i][q];
            fa[q] = fa[np] = nq;
            while(p && trans[c][p] == q) trans[c][p] = nq, p = fa[p];
        }
    }
}

int main(RG int argc, RG char* argv[]){
    scanf(" %s", s), n = strlen(s);
    for(RG int i = 0; i < n; ++i) Extend(s[i] - 'a');
    return 0;
}

原文地址：https://www.cnblogs.com/cjoieryl/p/8870149.html