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:

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.

解題

func minDeletionSize(strs []string) int {
    ans := 0

    for i:=0; i<len(strs[0]); i++ {
        for j:=1; j<len(strs); j++ {
            if strs[j][i] < strs[j-1][i]{
                ans++
                break
            }
        }
    }

    return ans
}