題目傳送門

做法：

• 計算出每個狀態下的endpos，通過endpos在區間內統計maxlen[st] - minlen[st]+1
• 即 maxlen[st] - minlen[st]+1 = l[st] - l[slink[st]];
• 模板題

AC程式碼：

#include<bits/stdc++.h>
#define IO          ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0)
#define pb(x)       push_back(x)
#define sz(x)       (int)(x).size()
#define
 
 sc(x)       scanf("%d",&x)
#define abs(x)      ((x)<0 ? -(x) : x)
#define all(x)      x.begin(),x.end(
#define mk(x,y)     make_pair(x,y)
#define fin         freopen("in.txt","r",stdin)
#define fout        freopen("out.txt","w",stdout)
using namespace std;
typedef long long ll;
const int mod =
 
 1e9+7;
const double PI = 4*atan(1.0);
const int maxm = 1e8+5;
const int maxn = 1e5+5;
const int INF = 0x3f3f3f3f;
char s[maxn];
struct SuffixAutoMation{
	int last,cnt,len,num[maxn<<1],c[maxn<<1],rk[maxn<<1]; //num陣列 等價 endpos
	int trans[maxn<<1][26],slink[maxn<<1],l[maxn<<
 
1];
	int L,R;
	inline void init()
	{
		memset(c,0,sizeof(c));
		memset(trans,0,sizeof(trans));
		memset(num,0,sizeof(num));
		cnt = last = 1;
		slink[last] = l[last] = 0;
	}
	inline void add(int x)
	{
		int p = last,np = ++cnt;last = np;l[np] = l[p]+1;
		for(;p&&!trans[p][x];p = slink[p]) trans[p][x] = np;
		if(!p) slink[np] = 1;
		else{
			int q = trans[p][x];
			if(l[p]+1 == l[q]) slink[np] = q;
			else{
				int nq = ++cnt;l[nq] = l[p]+1;
				memcpy(trans[nq],trans[q],sizeof(trans[q]));
				slink[nq] = slink[q];
				slink[q] = slink[np] = nq;
				for(;trans[p][x] == q;p=slink[p]) trans[p][x] = nq;
			}
		}
		num[np] = 1;
	}
	inline void build()
	{
		scanf("%d %d",&L,&R);
		cnt = last = 1;
		len = strlen(s+1);
		for(int i=1;i<=len;i++) add(s[i]-'A');
	}
	inline void topsort()
	{
		for(int i=1;i<=cnt;i++) c[l[i]]++;
		for(int i=1;i<=cnt;i++) c[i]+=c[i-1];
		for(int i=1;i<=cnt;i++) rk[c[l[i]]--] = i;
		for(int i=cnt;i>=1;i--)  //自底向上更新
		{
			int x = rk[i];
			num[slink[x]]+=num[x];
		}
		ll res = 0;
		for(int i=1;i<=cnt;i++)
		{
			if(num[i]>=L && num[i]<=R) res+=l[i]-l[slink[i]];
		}
		printf("%lld\n",res);
	}
}sam;
int main()
{
	// fin;
	// IO;
	while(~scanf("%s",s+1))
	{
		sam.init();
		sam.build();
		sam.topsort();
	}
	return 0;
}