後綴數組

//後綴數組，尚有bug
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>

//#define rep(i, a, b) for(int i=a;i<b;i++)
using namespace std;
const int MAXN = 10000 + 5;
int n, m;
char s[MAXN];
int sa[MAXN], t[MAXN], tt[MAXN], c[MAXN];
int rk[MAXN], h[MAXN];

void build() {
    int *x = t, *y = tt;
    rep(i, 0, m)c[i] = 0;
    rep(i, 0, n)c[x[i] = s[i]]++;
    rep(i, 1, m)c[i] += c[i - 1];
    for (int i = n - 1; i >= 0; i--)sa[--c[x[i]]] = i;
    for (int p = 1; p <= n; p <<= 1) {
        int j = 0;
        rep(i, n - p, n)y[j++] = i;
        rep(i, 0, n)if (sa[i] >= p)y[j++] = sa[i] - p;
        rep(i, 0, m)c[i] = 0;
        rep(i, 0, n)c[x[y[i]]]++;
        rep(i, 1, m)c[i] += c[i - 1];
        for (int i = n - 1; i >= 0; i--)sa[--c[x[y[i]]]] = y[i];
        swap(x, y);
        j = 1;
        x[sa[0]] = 0;
        rep(i, 1, n)x[sa[i]] = y[sa[i - 1]] == y[sa[i]] && y[sa[i - 1] + p] == y[sa[i] + p] ? j - 1 : j++;
        if (j >= n)break;
        m = j;
    }
}

void geth() {
    int i, j, k;
    for (i = 0; i < n; i++)rk[sa[i]] = i;
    for (i = 0; i < n; h[rk[i++]] = k)
        for (k ? k-- : 0, j = sa[rk[i] - 1]; s[i + k] == s[j + k]; k++);
}


int main() {

    return 0;
}

 

#include <bits/stdc++.h>

using namespace std;

const int maxn = 100000 * 2 + 5;

int wa[maxn], wb[maxn], cnt[maxn];

void da(const int *r, int *sa, int n, int m) {
    int *x = wa, *y = wb;
    memset(cnt, 0, sizeof(cnt));
    for (int i = 0; i < n; i++) cnt[x[i] = r[i]]++;
    for (int i = 1; i < m; i++) cnt[i] += cnt[i - 1];
    for (int i = n - 1; i >= 0; i--) sa[--cnt[x[i]]] = i;
    for (int j = 1, p = 1; p < n; j *= 2, m = p) {
        p = 0;
        for (int i = n - j; i < n; i++) y[p++] = i;
        for (int i = 0; i < n; i++) {
            if (sa[i] >= j) {
                y[p++] = sa[i] - j;
            }
        }
        memset(cnt, 0, sizeof(cnt));
        for (int i = 0; i < n; i++) cnt[x[y[i]]]++;
        for (int i = 1; i < m; i++) cnt[i] += cnt[i - 1];
        for (int i = n - 1; i >= 0; i--) sa[--cnt[x[y[i]]]] = y[i];
        swap(x, y);
        p = 1;
        x[sa[0]] = 0;
        for (int i = 1; i < n; i++)
            if (y[sa[i - 1]] == y[sa[i]] && y[sa[i - 1] + j] == y[sa[i] + j]) {
                x[sa[i]] = p - 1;
            } else {
                x[sa[i]] = p;
                p++;
            }

    }
}

int rank[maxn], height[maxn];

void calheight(const int *r, int *sa, int n) {
    for (int i = 1; i <= n; i++) {
        rank[sa[i]] = i;
    }
    int p = 0;
    for (int i = 0; i < n; i++) {
        if (p)p--;
        while (r[i + p] == r[sa[rank[i] - 1] + p]) {
            p++;
        }
        height[rank[i]] = p;
    }
}

char s[maxn];
int r[maxn], sa[maxn];

int main() {

    scanf("%s", s);
    int n = strlen(s);

    for (int i = 0; i < n; i++) r[i] = r[i + n] = s[i];
    n *= 2;
    r[n] = 0;

    da(r, sa, n + 1, CHAR_MAX + 1);

    calheight(r, sa, n);

    for (int i = 2; i <= n; i++)
        if (height[i] > ans)
            if ((j < sa[i - 1] && j > sa[i]) || (j > sa[i - 1] && j < sa[i]))
                ans = height[i];
    printf("%d\n", ans);
    return 0;
}