diff options
Diffstat (limited to 'datastructures')
| -rw-r--r-- | datastructures/datastructures.tex | 4 | ||||
| -rw-r--r-- | datastructures/sparseTable.cpp | 27 |
2 files changed, 29 insertions, 2 deletions
diff --git a/datastructures/datastructures.tex b/datastructures/datastructures.tex index 87d2a6d..b3683bf 100644 --- a/datastructures/datastructures.tex +++ b/datastructures/datastructures.tex @@ -13,8 +13,8 @@ \lstinputlisting{datastructures/fenwickTree.cpp} \lstinputlisting{datastructures/fenwickTreeNiklas.cpp} -\subsection{Range Minimum Query} -\lstinputlisting{datastructures/RMQ.cpp} +\subsection{Sparse Table} +\lstinputlisting{datastructures/sparseTable.cpp} \subsection{STL-Tree} \lstinputlisting{datastructures/stlTree.cpp} diff --git a/datastructures/sparseTable.cpp b/datastructures/sparseTable.cpp new file mode 100644 index 0000000..52867de --- /dev/null +++ b/datastructures/sparseTable.cpp @@ -0,0 +1,27 @@ +struct SparseTable { + int st[MAX_N][MAX_LOG + 1], log[MAX_N + 1]; // Achtung: 2^MAX_LOG > MAX_N + vector<int> *a; + + // Funktion muss idempotent sein! Hier Minimum. + bool better(int lidx, int ridx) { return a->at(lidx) <= a->at(ridx); } + + void init(vector<int> *vec) { + a = vec; + for (int i = 0; i < (int)a->size(); i++) st[i][0] = i; + for (int j = 1; j <= MAX_LOG; j++) { + for (int i = 0; i + (1 << j) <= (int)a->size(); i++) { + st[i][j] = better(st[i][j - 1], st[i + (1 << (j - 1))][j - 1]) + ? st[i][j - 1] : st[i + (1 << (j - 1))][j - 1]; + }} + + log[1] = 0; + for (int i = 2; i <= MAX_N; i++) log[i] = log[i/2] + 1; + } + + // Gibt Index des Ergebnisses in [l,r]. Laufzeit: O(1) + int queryIdempotent(int l, int r) { + int j = log[r - l + 1]; + return better(st[l][j], st[r - (1 << j) + 1][j]) + ? st[l][j] : st[r - (1 << j) + 1][j]; + } +}; |