BZOJ3238【后缀数组】【单调栈】

/* I will wait for you */  
  
#include <cstdio>  
#include <cstdlib>  
#include <cstring>  
#include <cmath>  
#include <ctime>  
#include <algorithm>  
#include <iostream>  
#include <fstream>  
#include <vector>  
#include <queue>  
#include <deque>  
#include <set>  
#include <map>  
#include <string>  
#define make make_pair  
#define fi first  
#define se second  
  
using namespace std;  
  
typedef long long ll;  
typedef unsigned long long ull;  
typedef pair<int, int> pii;  
  
const int maxn = 1000010;  
const int maxm = 1010;  
const int maxs = 26;  
const int inf = 0x3f3f3f3f;  
const int P = 1000000007;  
const double error = 1e-9;  
  
inline ll read() 
{  
    	ll x = 0, f = 1; 
	char ch = getchar();  
    	while (ch < '0' || ch > '9') 
		f = (ch == '-' ? -1 : 1), ch = getchar();  
    	while (ch >= '0' && ch <= '9')
	    	x = x * 10 + ch - '0', ch = getchar();  
    	return x * f;  
} 

struct Sa 
{
	int k[2],pos;
	bool operator != (const Sa b) {
		return k[0] != b.k[0] || k[1] != b.k[1];
	}
} x[maxn], y[maxn];

int n, c[maxn], rank[maxn], sa[maxn], q[maxn];
ll ans, up[maxn], down[maxn], hi[maxn];
char s[maxn];

void work() 
{
	for (int i = 0; i <= n; i++)
		c[i] = 0;
	for (int i = 0; i < n; i++) 
		c[s[i]]++;
	for (int i = 1; i <= n; i++) 
		c[i] += c[i - 1];
	for (int i = 0; i < n; i++) 
		rank[i] = c[s[i] - 1];
	
	for (int k = 1; k < n; k <<= 1) {
		for (int i = 0; i < n; i++) {
			x[i].k[0] = rank[i];
			x[i].k[1] = (i + k < n) ? 
			    rank[i + k] + 1: 0;
			x[i].pos = i;
		}
		
		for (int m = 1; m >= 0; m--) {
			for (int i = 0; i <= n; i++)
				c[i] = 0;
			for (int i = 0; i < n; i++) 
				c[x[i].k[m]]++;
			for (int i = 1; i <= n; i++)	
				c[i] += c[i - 1];
			for (int i = n - 1; i >= 0; i--) 
				y[--c[x[i].k[m]]] = x[i];
			for (int i = 0; i < n; i++)
				x[i] = y[i];
		}
		
		for (int i = 0; i < n; i++)
			rank[x[i].pos] = i ? rank[x[i - 1].pos] 
			    + (x[i] != x[i - 1]) : 0;
	}
	
	for (int i = 0; i < n; i++) sa[rank[i]] = i;
	
	for (int i = 0, h = 0; i < n; i++) {
		h = max(h - 1, 0);
		for (; rank[i] && s[i + h] == 
		     s[sa[rank[i] - 1] + h]; h++);
		hi[rank[i]] = rank[i] ? h : 0;
	}  
}

int main() 
{
	scanf("%s", s), n = strlen(s);
	
	for (int i = 0; i < n; i++) 
		s[i] -= 'a' - 1;
	
	work();
	
	q[0] = 0;
	for (int i = 1, top = 0; i < n; i++) {
		while (top && hi[q[top]] >= hi[i]) top--;
		int t = q[top];
		up[i] = up[t] + (i - t) * hi[i];
		q[++top] = i;
	}
	
	q[0] = n;
	for (int i = n - 1, top = 0; i >= 0; i--) {
		while (top && hi[q[top]] >= hi[i]) top--;
		int t = q[top];
		down[i] = down[t] + (t - i) * hi[i];
		q[++top] = i;
	}
	
	ans = (ll) n * (n + 1) * (n - 1) / 2;
	
	for (int i = 0; i < n; i++) ans -= up[i] + down[i];
	printf("%lld\n", ans);
			
	return 0;
}