Create sparse_table.cpp

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Anthony Wang 2019-08-02 10:53:39 -05:00 committed by GitHub
parent c9b31c10c2
commit ab2fe10480
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class sparse_table {
private: int st[20][100000];
public:
int log(int x) { return 32 - __builtin_clz(x) - 1; }
sparse_table(int N, int A[]) {
for (int i = 0; i < N; i++) st[i][0] = A[i];
for (int i = 0; i <= log(N); i++) {
for (int j = 0; j + (1 << i) < N; j++) st[i][j] = min(st[i - 1][j], st[i - 1][j + (1 << (i - 1))]);
}
}
int query(int i, int j) {
int k = log(j - i + 1);
return min(st[k][i], st[k][j - (1 << k) + 1]);
}
};