Create suffix_array.cpp

Changes

1 changed files (+30/-0)

• String/suffix_array.cpp (new)
  • @@ -0,0 +1,30 @@
    + #include <algorithm> + #include <vector> + #include <string> + using namespace std; + + vector<int> suffix_array(string &S) { + int N = S.length(); + vector<int> SA(N), rank(N); + for (int i = 0; i < N; i++) { + SA[i] = N - i - 1; + rank[i] = S[i]; + } + stable_sort(SA.begin(), SA.end(), [&S](int i, int j) { return S[i] < S[j]; }); + for (int t = 1; t < N; t <<= 1) { + vector<int> tmp(rank); + for (int i = 0; i < N; i++) { + bool s = i && SA[i - 1] + t < N && tmp[SA[i]] == tmp[SA[i - 1]] && tmp[SA[i] + t >> 1] == tmp[SA[i - 1] + t >> 1]; + rank[SA[i]] = s ? rank[SA[i - 1]] : i; + } + + tmp = SA; + vector<int> cnt(N); + for (int i = 0; i < N; i++) cnt[i] = i; + for (int i = 0; i < N; i++) { + int s = tmp[i] - t; + if (s >= 0) SA[cnt[rank[s]]++] = s; + } + } + return SA; + }