POJ3294--Life Forms 后缀数组+二分答案 大于k个字符串的最长公共子串

  1 #include <set>
  2 #include <map>
  3 #include <cmath>
  4 #include <ctime>
  5 #include <queue>
  6 #include <stack>
  7 #include <cstdio>
  8 #include <string>
  9 #include <vector>
 10 #include <cstdlib>
 11 #include <cstring>
 12 #include <iostream>
 13 #include <algorithm>
 14 using namespace std;
 15 typedef unsigned long long ull;
 16 typedef long long ll;
 17 const int inf = 0x3f3f3f3f;
 18 const double eps = 1e-8;
 19 const int M = 2e6+10;
 20 int s[M];
 21 int sa[M], tmp[M], rank[M], lcp[M], k, len;
 22 bool cmp(int i, int j)
 23 {
 24     if (rank[i] != rank[j])
 25         return rank[i] < rank[j];
 26     else
 27     {
 28         int x = i+k <= len ? rank[i+k] : -1;
 29         int y = j+k <= len ? rank[j+k] : -1;
 30         return x < y;
 31     }
 32 }
 33 void build_sa()
 34 {
 35     for (int i = 0; i <= len; i++)
 36     {
 37         sa[i] = i;
 38         rank[i] = i < len ? s[i] : -1;
 39     }
 40     for (k = 1; k <= len; k *= 2)
 41     {
 42         sort (sa, sa+len+1, cmp);
 43         tmp[sa[0]] = 0;
 44         for (int i = 1; i <= len; i++)
 45         {
 46             tmp[sa[i]] = tmp[sa[i-1]] + (cmp(sa[i-1], sa[i]) ? 1 : 0);
 47         }
 48         for (int i = 0; i <= len; i++)
 49         {
 50             rank[i] = tmp[i];
 51         }
 52     }
 53 }
 54 void Get_Lcp()
 55 {
 56     for (int i = 0; i < len; i++)
 57     {
 58         rank[sa[i]] = i;
 59     }
 60     int h = 0;
 61     lcp[0] = 0;
 62     for (int i = 0; i <  len; i++)
 63     {
 64         int j = sa[rank[i]-1];
 65         if (h > 0)
 66             h--;
 67         for (; i+h < len && j+h < len; h++)
 68             if (s[i+h] != s[j+h])
 69                 break;
 70         lcp[rank[i]] = h;
 71     }
 72 }
 73 int vis[110], pos[M];
 74 int ans[M], tot;
 75 int Stack[M], top;
 76 bool solve (int x, int n)
 77 {
 78     int minv = inf;
 79     int cnt = 0;
 80     bool flag = false;
 81     for (int i = 0; i <= len+1; i++)
 82     {
 83         if (lcp[i] < x)
 84         {
 85 
 86             if ( cnt+ (!vis[pos[sa[i-1]]]) > n/2 && (minv != inf && minv >= x))
 87             {
 88                 if (!flag )
 89                     tot = 0;
 90                 flag = true;
 91                 ans[tot++] = sa[i-1];
 92             }
 93             minv = inf;
 94             cnt = 0;
 95             memset(vis, 0, sizeof (vis));
 96             continue;
 97         }
 98         if ( vis[pos[sa[i-1]]]==0)
 99         {
100             cnt++;
101 
102         }
103         vis[pos[sa[i-1]]] = 1;
104         minv = min(minv, lcp[i]);
105 
106     }
107     return tot > 0 && flag;
108 }
109 int string_len[110], c1;
110 void init()
111 {
112     c1 = tot = 0;
113     memset(vis, 0, sizeof (vis));
114     memset(string_len, 0, sizeof (string_len));
115 }
116 char cacaca[1100];
117 int main()
118 {
119 #ifndef ONLINE_JUDGE
120     freopen("in.txt","r",stdin);
121    // freopen("wa.txt","w",stdout);
122 #endif
123     int n, cas = 1;
124     while ( scanf ("%d", &n), n)
125     {
126         if (cas != 1)
127             printf("\n");
128         cas++;
129         init();
130         len = 0;
131         int del = 1;
132         for (int i = 0; i < n; i++)
133         {
134             scanf ("%s", cacaca);
135             int sub_len = strlen(cacaca);
136             for (int j = 0; j < sub_len; j++)
137             {
138                 s[len++] = cacaca[j];
139             }
140             s[len++] = M+del;
141             del++;
142             string_len[c1] = sub_len + string_len[c1-1];
143             if (c1)
144                 string_len[c1]++;
145             c1++;
146         }
147         if (n == 1)
148         {
149             for (int i = 0; i < len-1; i++)
150             {
151                 printf("%c", s[i]);
152             }
153             continue;
154         }
155         for (int i = 0, j = 0; i < len; i++)
156         {
157             if (i >= string_len[j])
158             {
159                 pos[i] = -1;
160                 j++;
161                 continue;
162             }
163             pos[i] = j+1;
164         }
165         build_sa();
166         Get_Lcp();
167 
168         int ua = 0, ub = M;
169         while (ua + 1 < ub)
170         {
171             int mid = (ua + ub) >> 1;
172             if (mid&&solve(mid, n) == true)
173             {
174 
175                 ua = mid;
176             }
177             else
178                 ub = mid;
179         }
180         if (tot == 0)
181             printf("?\n");
182         else
183         {
184             if (ua == 0)
185             {
186                 printf("?\n");
187                 continue;
188             }
189             for (int i = 0; i < tot; i++)
190             {
191                 for (int j = ans[i]; j < ans[i]+ua; j++)
192                 {
193                     printf("%c", s[j]);
194                 }
195                 printf("\n");
196             }
197         }
198     }
199     return 0;
200 }