23 lines
850 B
C++
23 lines
850 B
C++
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template<typename _Tp, typename _Op = function<_Tp(const _Tp&, const _Tp&)>> struct sparse_table {
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_Op op;
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vector<vector<_Tp>> st;
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template <typename ReverseIterator>
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sparse_table(ReverseIterator __first, ReverseIterator __last, _Op&& __operation) {
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op = __operation;
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int n = distance(__first, __last);
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st = vector<vector<_Tp>>(n, vector<_Tp>(int(log2(n) + 1)));
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int i = n - 1;
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for (auto it = __first; it != __last; ++it) {
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st[i][0] = *it;
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for (int j = 1; i + (1 << j) <= n; ++j) {
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st[i][j] = op(st[i][j - 1], st[i + (1 << (j - 1))][j - 1]);
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}
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i -= 1;
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}
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}
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_Tp query(size_t __start, size_t __end) {
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int s = log2(__end - __start + 1);
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return op(st[__start][s], st[__end - (1 << s) + 1][s]);
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}
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};
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