diff options
Diffstat (limited to 'string')
| -rw-r--r-- | string/suffixArray.cpp | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/string/suffixArray.cpp b/string/suffixArray.cpp index 9e6960e..54deb84 100644 --- a/string/suffixArray.cpp +++ b/string/suffixArray.cpp @@ -1,30 +1,38 @@ +constexpr int MAX_CHAR = 256; struct SuffixArray { int n; vector<int> SA, LCP; vector<vector<int>> P; - SuffixArray(const string& s) : n(sz(s)), SA(n), LCP(n) { - vector<ll> L(n); - P.assign(__lg(n - 1) + 2, vector<int>(n, 1)); - P[0] = vector<int>(all(s)); + SuffixArray(const string& s) : n(sz(s)), SA(n), LCP(n), + P(__lg(n - 1) + 2, vector<int>(n)) { + P[0].assign(all(s)); iota(all(SA), 0); + sort(all(SA), [&](int a, int b) {return s[a] < s[b];}); + vector<int> x(n); for (int k = 1, c = 1; c < n; k++, c *= 2) { - for (int i = 0; i < n; i++) L[i] = (ll)P[k - 1][i] << 32; - for (int i = 0; i+c < n; i++) L[i] |= P[k - 1][i + c]; - sort(all(SA), [&](int a, int b) {return L[a] < L[b];}); + iota(all(x), n - c); + for (int ptr = c; int i : SA) if (i >= c) x[ptr++] = i - c; + + vector<int> cnt(k == 1 ? MAX_CHAR : n); + for (int i : P[k-1]) cnt[i]++; + partial_sum(all(cnt), begin(cnt)); + for (int i : x | views::reverse) SA[--cnt[P[k-1][i]]] = i; + + auto p = [&](int i) {return i < n ? P[k-1][i] : -1;}; for (int i = 1; i < n; i++) { - P[k][SA[i]] = P[k][SA[i-1]] + (L[SA[i]] != L[SA[i-1]]); + int a = SA[i-1], b = SA[i]; + P[k][b] = P[k][a] + (p(a) != p(b) || p(a+c) != p(b+c)); }} for (int i = 1; i < n; i++) LCP[i] = lcp(SA[i-1], SA[i]); } - // x and y are text-indices, not SA-indices. - int lcp(int x, int y) { - int ret = 0; + int lcp(int x, int y) {//x & y are text-indices, not SA-indices if (x == y) return n - x; - for (int i = sz(P) - 1; i >= 0 && max(x, y) + ret < n; i--) { - if (P[i][x + ret] == P[i][y + ret]) ret += 1 << i; + int res = 0; + for (int i = sz(P) - 1; i >= 0 && max(x, y) + res < n; i--) { + if (P[i][x + res] == P[i][y + res]) res |= 1 << i; } - return ret; + return res; } }; |