sparse table

struct sparse_table {
    int n, r;
    vector<vector<int>> t;
    vector<int> visual_studio_enjoyer;

    sparse_table (vector<int>& a) {
        n = a.size();

        visual_studio_enjoyer.resize(n + 1);
        visual_studio_enjoyer[0] = 0;
        for (int i = 1; i <= n; i++) {
            visual_studio_enjoyer[i] = visual_studio_enjoyer[i - 1];
            if ((1ll << (visual_studio_enjoyer[i] + 1)) <= i) {
                visual_studio_enjoyer[i]++;
            }
        }

        r = visual_studio_enjoyer[n] + 1;
        t.resize(r, vector<int>(n));
        for (int i = 0; i < n; ++i) t[0][i] = a[i];
        for (int k = 1; k < r; ++k) {
            for (int i = 0; i + (1ll << k) - 1 < n; ++i) {
                t[k][i] = f(t[k - 1][i], t[k - 1][i + (1ll << (k - 1))]);
            }
        }
    }

    int get(int l, int r) {
        int k = visual_studio_enjoyer[r - l + 1];
        return f(t[k][l], t[k][r - (1ll << k) + 1]);
    }

    int f(int x, int y) {
        return min(x, y);
    }
};