Search for a Range

• Time : $O(logn)$
• Space : $O(1)$

vector<int> Solution::searchRange(const vector<int> &A, int B) {
    auto l = lower_bound(begin(A), end(A), B) - begin(A);
    auto r = upper_bound(begin(A), end(A), B) - begin(A) - 1;
    if(0 <= l and l < A.size() and A[l] == B) return {l,r};
    return {-1,-1};
}