接上文
7..
given a string, determine if it is comprised of all unique character:
eg:
‘abcde’ -> True
‘abcda’ -> False
这个题，第一反应是将list转换成set, 比较length, 结果就很明白了。
def uni_chars(s):
return len(s) == len(set(s))
def uni_chars_2(s):
chars = set()
for letter in s:
if letter in chars:
return False
else:
chars.add(letter)
return True
print(uni_chars('abcde'))
print(uni_chars('abcda'))
print(uni_chars_2('abcde'))
print(uni_chars_2('abcda'))
8..
compress string:
eg: aaabbc -> a3b2c1
eg: AAAaaa -> A3a3
我记得以前看过某个博文讲压缩的时候讲过这个压缩.
def string_compress(s):
r = ''
l=len(s)
if l == 0:
return ''
if l == 1:
return s+"1"
cnt = 1
i = 1
while i < l:
if s[i] == s[i-1]:
cnt += 1
else:
r = r+s[i-1]+str(cnt)
cnt = 1
i += 1
r = r+s[i-1]+str(cnt)
return r
print(string_compress('AAB'))
9..
given a string of words, reverse all the words
这种题单行脚本就足够了
def rev_words(s):
return ' '.join(reversed(s.split()))
def rev_words_2(s):
return ' '.join(s.split()[::-1])
def rev_words_3(s):
words=[]
length = len(s)
spaces = [' ']
i = 0
while i < length:
if s[i] not in spaces:
word_start = i
while i < length and s[i] not in spaces:
i += 1
words.append(s[word_start:i])
i += 1
return ' '.join(reversed(words))
print(rev_words('Hi John, are you ready to go?'))
print(rev_words_2('Hi John, are you ready to go?'))
print(rev_words_3('Hi John, are you ready to go?'))
10..
Given an array of integers (positive and negative) find the largest continuous sum
这个题我很喜欢，有点意思，因此放在最后
def large_cont_sum(arr):
if len(arr)==0:
return 0
max_sum = current_sum = arr[0]
for num in arr[1:]:
current_sum = max(current_sum + num, num)
max_sum = max(current_sum, max_sum)
return max_sum
print(large_cont_sum([1,2,-1,3,4,10,10,-10,-1]))
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