2.2_en_route_salute.py

# En Route Salute
# ===========================

# Commander Lambda loves efficiency and hates anything that wastes time. She's a busy lamb, after all! She generously
# rewards henchmen who identify sources of inefficiency and come up with ways to remove them. You've spotted one such
# source, and you think solving it will help you build the reputation you need to get promoted.
#
# Every time the Commander's employees pass each other in the hall, each of them must stop and salute each other -
# one at a time - before resuming their path. A salute is five seconds long, so each exchange of salutes takes a full
# ten seconds (Commander Lambda's salute is a bit, er, involved). You think that by removing the salute requirement,
# you could save several collective hours of employee time per day. But first, you need to show her how bad the
# problem really is.
#
# Write a program that counts how many salutes are exchanged during a typical walk along a hallway. The hall is
# represented by a string. For example: "--->-><-><-->-"
#
# Each hallway string will contain three different types of characters: '>', an employee walking to the right; '<',
# an employee walking to the left; and '-', an empty space. Every employee walks at the same speed either to right or
# to the left, according to their direction. Whenever two employees cross, each of them salutes the other. They then
# continue walking until they reach the end, finally leaving the hallway. In the above example, they salute 10 times.
#
# Write a function answer(s) which takes a string representing employees walking along a hallway and returns the
# number of times the employees will salute. s will contain at least 1 and at most 100 characters, each one of -, >,
# or <.
#
# Test cases
# Input:
#
# ">----<"
#
# Output:
#
# 2
#
# Input:
#
# "<<>><"
#
# Output:
#
# 4
#
# Input:
#
# "--->-><-><-->-"
#
# Output:
#
# 5
#
# Input:
#
# "-<-><-->-"
#
# Output:
#
# 1
#
# Input:
#
# "-<->><-->>-<<->->"
#
# Output:
#
# 10

def solution(s):
    r = ans = 0
    for char in s:
        if char == '>':
            r += 1
        elif char == '<' and r > 0:
            ans += (r * 2)

    return ans


print(solution("<<>><"))
print(solution(">----<"))