Udacity-cs101-building-a-search-engine

课程3 字符串练习

练习2 文本替换

###############################################
#       Exercise by Websten from forums       #
###############################################
# To minimize errors when writing long texts with
# complicated expressions you could replace 
# the tricky parts with a marker. 
# Write a program that takes a line of text and 
# finds the first occurrence of a certain marker 
# and replaces it with a replacement text. 
# The resulting line of text should be stored in a variable. 
# All input data will be given as variables.
#
# Replace the first occurrence of marker in the line below.
# There will be at least one occurrence of the marker in the
# line of text. Put the answer in the variable 'replaced'.
# Hint: You can find out the length of a string by command
# len(string). We might test your code with different markers!

# Example 1
marker = "AFK"
replacement = "away from keyboard"
line = "I will now go to sleep and be AFK until lunch time tomorrow."

# Example 2 # uncomment this to test with different input
#marker = "EY"
#replacement = "Eyjafjallajokull"
#line = "The eruption of the volcano EY in 2010 disrupted air travel in Europe for 6 days."

###
# YOUR CODE BELOW. DO NOT DELETE THIS LINE
###

replaced = line.replace(marker,replacement)
print replaced
# Example 1 output should be:
#>>> I will now go to sleep and be away from keyboard until lunch time tomorrow.
# Example 2 output should be:
#>>> The eruption of the volcano Eyjafjallajokull in 2010 disrupted air travel in Europe for 6 days.

练习6 回文

###############################################
#       Exercise by Websten from forums       #
###############################################
# A palindrome is a word or a phrase that reads 
# the same backwards as forwards. Make a program 
# that checks if a word is a palindrome. 
# If the word is a palindrome, print 0 to the terminal,
# -1 otherwise. 
# The word contains lowercase letters a-z and 
# will be at least one character long.
#
### HINT! ###
# You can read a string backwards with the following syntax:
# string[::-1] - where the "-1" means one step back.
# This exercise can be solved with only unit 1 knowledge
# (no loops or conditions)

word = "madam"
# test case 2
# word = "madman" # uncomment this to test

###
# YOUR CODE HERE. DO NOT DELETE THIS LINE OR ADD A word DEFINITION BELOW IT.
###



is_palindrome = word[::-1].find(word)


# TESTING
print is_palindrome
# >>> 0  # outcome if word == "madam"
# >>> -1 # outcome if word == "madman"