[HDU3518]Boring counting（后缀数组）

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 #define N 1005
 5 #define max(x, y) ((x) > (y) ? (x) : (y))
 6 #define min(x, y) ((x) < (y) ? (x) : (y))
 7 
 8 int len, n, m, ans;
 9 int buc[N], x[N], y[N], sa[N], ran[N], height[N];
10 char s[N];
11 
12 inline void build_sa()
13 {
14     int i, k, p;
15     for(i = 0; i < m; i++) buc[i] = 0;
16     for(i = 0; i < len; i++) buc[x[i] = s[i]]++;
17     for(i = 1; i < m; i++) buc[i] += buc[i - 1];
18     for(i = len - 1; i >= 0; i--) sa[--buc[x[i]]] = i;
19     for(k = 1; k <= len; k <<= 1)
20     {
21         p = 0;
22         for(i = len - 1; i >= len - k; i--) y[p++] = i;
23         for(i = 0; i < len; i++) if(sa[i] >= k) y[p++] = sa[i] - k;
24         for(i = 0; i < m; i++) buc[i] = 0;
25         for(i = 0; i < len; i++) buc[x[y[i]]]++;
26         for(i = 1; i < m; i++) buc[i] += buc[i - 1];
27         for(i = len - 1; i >= 0; i--) sa[--buc[x[y[i]]]] = y[i];
28         std::swap(x, y);
29         p = 1, x[sa[0]] = 0;
30         for(i = 1; i < len; i++)
31             x[sa[i]] = y[sa[i - 1]] == y[sa[i]] && y[sa[i - 1] + k] == y[sa[i] + k] ? p - 1 : p++;
32         if(p >= len) break;
33         m = p;
34     }
35 }
36 
37 inline void build_height()
38 {
39     int i, j, k = 0;
40     for(i = 0; i < len; i++) ran[sa[i]] = i;
41     for(i = 0; i < len; i++)
42     {
43         if(!ran[i]) continue;
44         if(k) k--;
45         j = sa[ran[i] - 1];
46         while(s[i + k] == s[j + k] && i + k < len && j + k < len) k++;
47         height[ran[i]] = k;
48     }
49 }
50 
51 inline void check(int k)
52 {
53     int Max, Min;
54     Max = Min = sa[0];
55     for(int i = 1; i < len; i++)
56         if(height[i] >= k)
57         {
58             Max = max(Max, sa[i]);
59             Min = min(Min, sa[i]);
60         }
61         else
62         {
63             ans += Max - Min >= k;
64             Max = Min = sa[i];
65         }
66     ans += Max - Min >= k;
67 }
68 
69 int main()
70 {
71     while(scanf("%s", s) != EOF)
72     {
73         if(s[0] == ‘#‘) break;
74         len = strlen(s);
75         m = 300;
76         build_sa();
77         build_height();
78         ans = 0;
79         for(int i = 1; i <= (len >> 1); i++) check(i);
80         printf("%d\n", ans);
81     }
82     return 0;
83 }