# Delete Columns To Make Sorted Problem

## Description

LeetCode Problem 944.

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:

1
2
3

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:

1
2
3
4
5
6
7

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:

1
2
3
4
5
6

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:

1
2
3
4
5
6
7

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.

## Sample C++ Code

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

class Solution {
public:
int minDeletionSize(vector<string>& A) {
int cnt = 0;
for (int i = 0; i < A[0].length(); i++) {
bool flag = false;
for (int j = 1; j < A.size(); j++){
if (A[j][i] < A[j-1][i])
flag = true;
}
if (flag)
cnt++;
}
return cnt;
}
};