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In an alien language, surprisingly they also use english lowercase letters, but possibly in a different order
. The order
of the alphabet is some permutation of lowercase letters.
Given a sequence of words
written in the alien language, and the order
of the alphabet, return true
if and only if the given words
are sorted lexicographicaly in this alien language.
Example 1:
Input: words = ["hello","leetcode"], order = "hlabcdefgijkmnopqrstuvwxyz"
Output: true
Explanation: As 'h' comes before 'l' in this language, then the sequence is sorted.
Example 2:
Input: words = ["word","world","row"], order = "worldabcefghijkmnpqstuvxyz"
Output: false
Explanation: As 'd' comes after 'l' in this language, then words[0] > words[1], hence the sequence is unsorted.
Example 3:
Input: words = ["apple","app"], order = "abcdefghijklmnopqrstuvwxyz"
Output: false
Explanation: The first three characters "app" match, and the second string is shorter (in size.) According to lexicographical rules "apple" > "app", because 'l' > '∅', where '∅' is defined as the blank character which is less than any other character (More info).
Note:
1 <= words.length <= 100
1 <= words[i].length <= 20
order.length == 26
- All characters in
words[i]
andorder
are english lowercase letters.
根据order里字母出现的顺序,判断words中的值是不是有序的,即是否words[0]<words[1]<...words[len(words)-1]
用python内建的enumerate函数:enumerate(list,start=0)
上述函数中,list是一个可迭代的对象,可以是列表,字典,文件对象等等。
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enumerate返回的是下标和item组成的元组:
a=['ab', 'bc', 'cc']
>>> list(enumerate(a))
[(0, 'ab'), (1, 'bc'), (2, 'cc')]
可以是字典
>>> dict(enumerate(a))
{0: 'ab', 1: 'bc', 2: 'cc'}
class Solution:
def isAlienSorted(self, words, order):
"""
:type words: List[str]
:type order: str
:rtype: bool
"""
dictm={}
# words=["word","world","row"]
#order="worldabcefghijkmnpqstuvxyz"
#dictm=dict(enumerate(order))
for k, i in enumerate(order):
dictm[i] = k
for i in range(len(words)-1):
b=0
x=words[i]
y=words[i+1]
for j in range (min(len(x),len(y))):
if dictm[x[j]] > dictm[y[j]]:
return False
if dictm[x[j]] < dictm[y[j]]:
b=1
break
if b==0 and len(x) > len(y):
return False
return True