pythonOff-by-oneHard

Binary search misses the last element

Time: 0:00

What it should do

binary_search(nums, target) should return the index of target in a sorted list, or -1 if it isn't there.

What goes wrong

It works for most values but returns -1 for some that are definitely present — searching for 9 in [1,3,5,7,9] gives -1.

Hints

This is an off-by-one errors bug

The loop that runs one time too many, the slice that drops the last item, the index that starts in the wrong place.