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#include <ios> #include <iostream> #include <string> #include <vector> inline bool leq(int a1, int a2, int b1, int b2) // lexicographic order { return (a1 < b1 || a1 == b1 && a2 <= b2); } // for pairs inline bool leq(int a1, int a2, int a3, int b1, int b2, int b3) { return (a1 < b1 || a1 == b1 && leq(a2, a3, b2, b3)); } // and triples // stably sort a[0..n-1] to b[0..n-1] with keys in 0..K from r static void radixPass(int *a, int *b, int *r, int n, int K) { // count occurrences int *c = new int[K + 1]; // counter array for (int i = 0; i <= K; i++) c[i] = 0; // reset counters for (int i = 0; i < n; i++) c[r[a[i]]]++; // count occurrences for (int i = 0, sum = 0; i <= K; i++) // exclusive prefix sums { int t = c[i]; c[i] = sum; sum += t; } for (int i = 0; i < n; i++) b[c[r[a[i]]]++] = a[i]; // sort delete[] c; } // find the suffix array SA of s[0..n-1] in {1..K}ˆn // require s[n]=s[n+1]=s[n+2]=0, n>=2 void suffixArray(int *s, int *SA, int n, int K) { int n0 = (n + 2) / 3, n1 = (n + 1) / 3, n2 = n / 3, n02 = n0 + n2; int *s12 = new int[n02 + 3]; s12[n02] = s12[n02 + 1] = s12[n02 + 2] = 0; int *SA12 = new int[n02 + 3]; SA12[n02] = SA12[n02 + 1] = SA12[n02 + 2] = 0; int *s0 = new int[n0]; int *SA0 = new int[n0]; // generate positions of mod 1 and mod 2 suffixes // the "+(n0-n1)" adds a dummy mod 1 suffix if n%3 == 1 for (int i = 0, j = 0; i < n + (n0 - n1); i++) if (i % 3 != 0) s12[j++] = i; // lsb radix sort the mod 1 and mod 2 triples radixPass(s12, SA12, s + 2, n02, K); radixPass(SA12, s12, s + 1, n02, K); radixPass(s12, SA12, s, n02, K); // find lexicographic names of triples int name = 0, c0 = -1, c1 = -1, c2 = -1; for (int i = 0; i < n02; i++) { if (s[SA12[i]] != c0 || s[SA12[i] + 1] != c1 || s[SA12[i] + 2] != c2) { name++; c0 = s[SA12[i]]; c1 = s[SA12[i] + 1]; c2 = s[SA12[i] + 2]; } if (SA12[i] % 3 == 1) { s12[SA12[i] / 3] = name; } // left half else { s12[SA12[i] / 3 + n0] = name; } // right half } // recurse if names are not yet unique if (name < n02) { suffixArray(s12, SA12, n02, name); // store unique names in s12 using the suffix array for (int i = 0; i < n02; i++) s12[SA12[i]] = i + 1; } else // generate the suffix array of s12 directly for (int i = 0; i < n02; i++) SA12[s12[i] - 1] = i; // stably sort the mod 0 suffixes from SA12 by their first character for (int i = 0, j = 0; i < n02; i++) if (SA12[i] < n0) s0[j++] = 3 * SA12[i]; radixPass(s0, SA0, s, n0, K); // merge sorted SA0 suffixes and sorted SA12 suffixes for (int p = 0, t = n0 - n1, k = 0; k < n; k++) { #define GetI() (SA12[t] < n0 ? SA12[t] * 3 + 1 : (SA12[t] - n0) * 3 + 2) int i = GetI(); // pos of current offset 12 suffix int j = SA0[p]; // pos of current offset 0 suffix if (SA12[t] < n0 ? // different compares for mod 1 and mod 2 suffixes leq(s[i], s12[SA12[t] + n0], s[j], s12[j / 3]) : leq(s[i], s[i + 1], s12[SA12[t] - n0 + 1], s[j], s[j + 1], s12[j / 3 + n0])) { // suffix from SA12 is smaller SA[k] = i; t++; if (t == n02) // done --- only SA0 suffixes left for (k++; p < n0; p++, k++) SA[k] = SA0[p]; } else { // suffix from SA0 is smaller SA[k] = j; p++; if (p == n0) // done --- only SA12 suffixes left for (k++; t < n02; t++, k++) SA[k] = GetI(); } } delete[] s12; delete[] SA12; delete[] SA0; delete[] s0; } int main() { std::ios::sync_with_stdio(false); std::cin.tie(0); // std::string str; // str.reserve(100001); // std::getline(std::cin, str); std::string str = "99 bottles of beer."; std::vector<int> data; data.reserve(str.size()); for (auto ch : str) { data.emplace_back(ch - 32); } std::vector<int> res(data.size()); suffixArray(data.data(), res.data(), str.size(), 127-31); for (int i = 0; i < res.size(); ++i) { std::cout << (res[i] + 1) << " "; } std::cout << "\n"; return 0; }
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