POJ 2774 (后缀数组 最长公共字串) Long Long Message

用一个特殊字符将两个字符串连接起来，然后找最大的height，而且要求这两个相邻的后缀的第一个字符不能在同一个字符串中。

 1 #include <cstdio>

 2 #include <cstring>

 3 #include <algorithm>

 4 using namespace std;

 5 

 6 const int maxn = 200000 + 10;

 7 

 8 char s[maxn];

 9 int n;

10 int sa[maxn], rank[maxn], height[maxn];

11 int t[maxn], t2[maxn], c[maxn];

12 

13 void build_sa(int n, int m)

14 {

15     int i, *x = t, *y = t2;

16     for(i = 0; i < m; i++) c[i] = 0;

17     for(i = 0; i < n; i++) c[x[i] = s[i]]++;

18     for(i = 1; i < m; i++) c[i] += c[i - 1];

19     for(i = n - 1; i >= 0; i--) sa[--c[x[i]]] = i;

20     for(int k = 1; k <= n; k <<= 1)

21     {

22         int p = 0;

23         for(i = n - k; i < n; i++) y[p++] = i;

24         for(i = 0; i < n; i++) if(sa[i] >= k) y[p++] = sa[i] - k;

25         for(i = 0; i < m; i++) c[i] = 0;

26         for(i = 0; i < n; i++) c[x[y[i]]]++;

27         for(i = 1; i < m; i++) c[i] += c[i - 1];

28         for(i = n - 1; i >= 0; i--) sa[--c[x[y[i]]]] = y[i];

29         swap(x, y);

30         p = 1; x[sa[0]] = 0;

31         for(i = 1; i < n; i++)

32             x[sa[i]] = y[sa[i]]==y[sa[i-1]] && y[sa[i]+k]==y[sa[i-1]+k] ? p - 1 : p++;

33         if(p >= n) break;

34         m = p;

35     }

36 }

37 

38 void build_height()

39 {

40     int k = 0;

41     for(int i = 1; i <= n; i++) rank[sa[i]] = i;

42     for(int i = 0; i < n; i++)

43     {

44         if(k) k--;

45         int j = sa[rank[i] - 1];

46         while(s[i + k] == s[j + k]) k++;

47         height[rank[i]] = k;

48     }

49 }

50 

51 int main()

52 {

53     //freopen("in.txt", "r", stdin);

54 

55     scanf("%s", s);

56     int pos = strlen(s);

57     s[pos] = 1;

58     scanf("%s", s + pos + 1);

59     n = strlen(s);

60 

61     build_sa(n + 1, 256);

62     build_height();

63 

64     int ans = 0;

65     for(int i = 2; i <= n; i++)

66     {

67         if(height[i] > ans)

68         {

69             if((sa[i]>pos && sa[i-1]<pos) || (sa[i]<pos&&sa[i-1]>pos))

70                 ans = height[i];

71         }

72     }

73 

74     printf("%d\n", ans);

75 

76     return 0;

77 }

代码君