明显要用求SA再求h，而lcp(i,j)就等于i到j之间最小的h
用f[i]表示i跟比i大的后缀的lcp的和，然后用单调栈维护最小值就好了（有点像DP？）
1 #include<bits/stdc++.h> 2 #define inc(i,l,r) for(int i=l;i<=r;i++) 3 #define dec(i,l,r) for(int i=l;i>=r;i--) 4 #define link(x) for(edge *j=h[x];j;j=j->next) 5 #define mem(a) memset(a,0,sizeof(a)) 6 #define inf 1e9 7 #define ll long long 8 #define succ(x) (1<<x) 9 #define NM 500000+5 10 using namespace std; 11 int read(){ 12 int x=0,f=1;char ch=getchar(); 13 while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();} 14 while(isdigit(ch))x=x*10+ch-'0',ch=getchar(); 15 return x*f; 16 } 17 char st[NM]; 18 int n,m,tmp[NM],top[NM],rank[NM],sa[NM],h[NM]; 19 ll f[NM],ans; 20 stack<int >s; 21 void getsa(){ 22 int j;m=256; 23 inc(i,0,n)top[rank[i]=(int)st[i]]++; 24 inc(i,1,m)top[i]+=top[i-1]; 25 inc(i,0,n)sa[--top[rank[i]]]=i; 26 // inc(i,0,n)printf("%d ",sa[i]);printf(" "); 27 for(int k=1;k<=n;k<<=1){ 28 inc(i,0,n){ 29 j=sa[i]-k; 30 if(j<0)j+=n+1; 31 tmp[top[rank[j]]++]=j; 32 } 33 // inc(i,0,n)printf("%d ",tmp[i]);printf(" "); 34 sa[tmp[top[0]=0]]=j=0; 35 inc(i,1,n){ 36 if(rank[tmp[i-1]]!=rank[tmp[i]]||rank[tmp[i]+k]!=rank[tmp[i-1]+k]) 37 top[++j]=i; 38 sa[tmp[i]]=j; 39 } 40 memcpy(rank,sa,sizeof(sa)); 41 memcpy(sa,tmp,sizeof(tmp)); 42 if(j>=n)break; 43 } 44 j=0; 45 // inc(i,0,n)printf("%d ",sa[i]);printf(" "); 46 inc(i,0,n)if(rank[i]){ 47 if(j)j--; 48 while(st[i+j]==st[sa[rank[i]-1]+j]) 49 j++; 50 h[rank[i]]=j; 51 } 52 // inc(i,0,n)printf("%d ",h[i]);printf(" "); 53 } 54 int main(){ 55 freopen("data.in","r",stdin); 56 scanf("%s",st); 57 n=strlen(st);st[n+1]='$'; 58 getsa(); 59 ans=(ll)(n+1)*(n-1)*n>>1; 60 dec(i,n,0){ 61 while(!s.empty()&&h[s.top()]>h[i])s.pop(); 62 int t=s.empty()?n+1:s.top(); 63 f[i]=(ll)h[i]*(t-i)+f[t]; 64 ans-=f[i]<<1;s.push(i); 65 } 66 // inc(i,0,n)printf("%lld ",f[i]);printf(" "); 67 printf("%lld",ans); 68 return 0; 69 }