944 - Delete Columns to Make Sorted.

Easy

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 follows:

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.