Description
You are given an array of n strings strs, all of the same length.
The strings can be arranged such that there is one on each line, making a grid. For example, strs = [“abc”, “bce”, “cae”] can be arranged as:
abc
bce
cae
You want to delete the columns that are not sorted lexicographically. In the above example (0-indexed), columns 0 (‘a’, ‘b’, ‘c’) and 2 (‘c’, ‘e’, ‘e’) are sorted while column 1 (‘b’, ‘c’, ‘a’) is not, so you would delete column 1.
Return the number of columns that you will delete.
Example 1:
Input: strs = ["cba","daf","ghi"]
Output: 1
Explanation: The grid looks as follows:
cba
daf
ghi
Columns 0 and 2 are sorted, but column 1 is not, so you only need to delete 1 column.
Example 2:
Input: strs = ["a","b"]
Output: 0
Explanation: The grid looks as follows:
a
b
Column 0 is the only column and is sorted, so you will not delete any columns.
Example 3:
Input: strs = ["zyx","wvu","tsr"]
Output: 3
Explanation: The grid looks as follows:
zyx
wvu
tsr
All 3 columns are not sorted, so you will delete all 3.
Constraints:
- n == strs.length
- 1 <= n <= 100
- 1 <= strs[i].length <= 1000
- strs[i] consists of lowercase English letters.
分析
题目的意思是：给定一个字符串数组，把这些字符串排列成矩阵，删除那些没有按照字母顺序排序的列。
- 思路也很直接，直接把每一列取出来，然后排序后看是否和原来的字符串相等就可以判断了，然后统计一下不等的数量，维护更新res。
代码
class Solution:
def minDeletionSize(self, strs: List[str]) -> int:
res=0
for i in range(len(strs[0])):
s=''.join(item[i] for item in strs)
s1=''.join(sorted(s))
if(s!=s1):
res+=1
return res