【AHOI2013】bzoj3238 差异

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define LL long long
const int maxn=500010;
char s[maxn];
int sa[maxn],rank[maxn],height[maxn],f[maxn],sta[maxn],val[maxn],cnt[maxn],n;
int main()
{
int p,m=26,top;
LL ans=0,now=0;
scanf("%s",s+1);
n=strlen(s+1);
for (int i=1;i<=n;i++) cnt[rank[i]=s[i]-'a'+1]++;
for (int i=2;i<=m;i++) cnt[i]+=cnt[i-1];
for (int i=n;i;i--) sa[cnt[rank[i]]--]=i;
for (int k=1;;k<<=1)
{
p=0;
for (int i=n-k+1;i<=n;i++) f[++p]=i;
for (int i=1;i<=n;i++)
if (sa[i]>k) f[++p]=sa[i]-k;
for (int i=1;i<=m;i++) cnt[i]=0;
for (int i=1;i<=n;i++) cnt[rank[f[i]]]++;
for (int i=2;i<=m;i++) cnt[i]+=cnt[i-1];
for (int i=n;i;i--) sa[cnt[rank[f[i]]]--]=f[i];
for (int i=1;i<=n;i++) f[i]=rank[i];
rank[sa[1]]=1;
for (int i=2;i<=n;i++)
if (f[sa[i]]!=f[sa[i-1]]||f[sa[i]+k]!=f[sa[i-1]+k])
rank[sa[i]]=rank[sa[i-1]]+1;
else
rank[sa[i]]=rank[sa[i-1]];
m=rank[sa
];
if (m>=n) break;
}
for (int i=1;i<=n;i++)
{
height[rank[i]]=height[rank[i-1]];
if (height[rank[i]]) height[rank[i]]--;
while (s[i+height[rank[i]]]==s[sa[rank[i]-1]+height[rank[i]]])
height[rank[i]]++;
}
sta[top=1]=1;
for (int i=2;i<=n;i++)
{
p=i;
while (top&&height[i]<=val[top])
{
now-=(LL)(p-sta[top])*(val[top]-height[i]);
p=sta[top];
top--;
}
sta[++top]=p;
val[top]=height[i];
now+=height[i];
ans-=now;
}
//printf("%lld\n",-ans);
ans*=2;
for (int i=1;i<=n;i++) ans+=(LL)3*i*(i-1)/2;
printf("%lld\n",ans);
}