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Create sparse_table.cc

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Ariel 2024-02-18 16:21:42 +08:00 committed by GitHub
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template<typename _Tp, typename _Op = function<_Tp(const _Tp&, const _Tp&)>> struct sparse_table {
_Op op;
vector<vector<_Tp>> st;
template <typename ReverseIterator>
sparse_table(ReverseIterator __first, ReverseIterator __last, _Op&& __operation) {
op = __operation;
int n = distance(__first, __last);
st = vector<vector<_Tp>>(n, vector<_Tp>(int(log2(n) + 1)));
int i = n - 1;
for (auto it = __first; it != __last; ++it) {
st[i][0] = *it;
for (int j = 1; i + (1 << j) <= n; ++j) {
st[i][j] = op(st[i][j - 1], st[i + (1 << (j - 1))][j - 1]);
}
i -= 1;
}
}
_Tp query(size_t __start, size_t __end) {
int s = log2(__end - __start + 1);
return op(st[__start][s], st[__end - (1 << s) + 1][s]);
}
};