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Suffix Array (DC3) With LCP

Jul 30th, 2013
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C++ 1.35 KB | None | 0 0
  1. char str [MAX_N];
  2. int N, m, SA [MAX_N], LCP [MAX_N];
  3. int x [MAX_N], y [MAX_N], w [MAX_N], c [MAX_N];
  4.  
  5. inline bool cmp (const int a, const int b, const int l) { return (y [a] == y [b] && y [a + l] == y [b + l]); }
  6.  
  7. void Sort () {
  8.     for (int i = 0; i < m; ++i) w [i] = 0;
  9.     for (int i = 0; i < N; ++i) ++w [x [y [i]]];
  10.     for (int i = 0; i < m - 1; ++i) w [i + 1] += w [i];
  11.     for (int i = N - 1; i >= 0; --i) SA [--w [x [y [i]]]] = y [i];
  12. }
  13.  
  14. void DA () {
  15.     ++N;
  16.     for (int i = 0; i < N; ++i) x [i] = str [i], y[i] = i;
  17.     Sort ();
  18.     for (int i, j = 1, p = 1; p < N; j <<= 1, m = p) {
  19.         for (p = 0, i = N - j; i < N; i++) y [p++] = i;
  20.         for (int k = 0; k < N; ++k) if (SA [k] >= j) y [p++] = SA [k] - j;
  21.         Sort ();
  22.         for (swap (x, y), p = 1, x [SA [0]] = 0, i = 1; i < N; ++i) x [SA [i]] = cmp (SA [i - 1], SA [i], j) ? p - 1 : p++;
  23.     }
  24.     for (int i = 1; i < N; ++i) SA [i - 1] = SA [i]; --N;
  25. }
  26.  
  27. void kasaiLCP () {
  28.     for (int i = 0; i < N; ++i) c [SA [i]] = i;
  29.     LCP [0] = 0;
  30.     for (int i = 0, h = 0; i < N; ++i) if (c[i] > 0) {
  31.             int j = SA [c [i] - 1];
  32.             while (i + h < N && j + h < N && str [i + h] == str [j + h]) ++h;
  33.             LCP [c [i]] = h;
  34.             if (h > 0) --h;
  35.         }
  36. }
  37.  
  38. void suffixArray () {
  39.     m = 256;
  40.     N = strlen (str);
  41.     DA ();
  42.     kasaiLCP ();
  43. }
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