样例一

期望答案552，输出1092

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<string>
#include<map>
using namespace std;

const int N = 1e6+100;

int n, last, size, edge_cnt, head[N << 1];
char str[N];

struct SAM_state {
    int len, link, cnt, next[26];
    SAM_state(): len(0), link(-1), cnt(0) {
        for(int i = 0; i < 26; i++)
            next[i] = -1;
    }
} st[N << 1];

struct Edge {
    int to, next;
    Edge(): next(-1) {}
} edge[N << 1];

void init() {
    st[0].len = 0;
    st[0].link = -1;
    size++;
    last = 0;
    memset(head, -1, sizeof(head));
}

void sam_extend(char c) {
    int cur = size++;
    st[cur].cnt = 1;
    st[cur].len = st[last].len + 1;
    int p = last;
    while(p != -1 && st[p].next[c - 'a'] == -1) {
        st[p].next[c - 'a'] = cur;
        p = st[p].link;
    }
    if(p == -1) {
        st[cur].link = 0;
    } else {
        int q = st[p].next[c - 'a'];
        if(st[p].len + 1 == st[q].len) {
            st[cur].link = q;
        } else {
            int clone = size++;
            st[clone] = st[q];
            st[clone].len = st[p].len + 1;
            while(p != -1 && st[p].next[c - 'a'] == q) {
                st[p].next[c - 'a'] = clone;
                p = st[p].link;
            }
            st[cur].link = clone;
            st[q].link = clone;
        }
    }
    last = cur;
}

void add_edge(int from, int to) {
    edge_cnt++;
    edge[edge_cnt].to = to;
    edge[edge_cnt].next = head[from];
    head[from] = edge_cnt;
}

int dfs(int k) {
    for(int i = head[k]; i != -1; i = edge[i].next)
        st[k].cnt += dfs(edge[i].to);
    return st[k].cnt;
}

int main() {
    scanf("%s", str + 1);
    n = strlen(str + 1);

    init();
    for(int i = 1; i <= n; i++)
        sam_extend(str[i]);

    for(int i = 0; i < size; i++)
        if(st[i].link != -1)
            add_edge(st[i].link, i);

    dfs(0);

    int ans = 0;
    for(int i = 1; i < size; i++)
        if(st[i].cnt > 1 && st[i].cnt * st[i].len > ans)
            ans = st[i].cnt * st[i].len;
    printf("%d\n", ans);
    return 0;
}