function for finding last item less-than-or-equal to, like lower_bound

Question

Is there a function in that uses binary search, like lower_bound but that returns the last item less-than-or-equal-to according to a given predic

Answer 1

A simple implementation in Python:

def bi_search(arr, target):
    """
    index of the last element which <= target
    """

    lo, hi = 0, len(arr)
    while lo < hi:
        mid = lo + (hi - lo) // 2
        if arr[mid] <= target:
            lo = mid + 1
        else:
            hi = mid
    return lo - 1