Problem

Given a list of integers, write a function that returns the index of the first number that is larger than the given target number. If there is no such number, return -1.
Example input: 
[1, 2, 3, 4, 5], target = 3
Example output: 
2

Solution

def find_first_larger(lst, target):
    for i in range(len(lst)):
        if lst[i] > target:
            return i
    return -1

# This solution is optimal because it is O(n) time complexity.
# It is also optimal because it is O(1) space complexity.