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 }
