LeetCode-in-Java

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.

Solution

public class Solution {
    public int minDeletionSize(String[] strs) {
        int count = 0;
        for (int i = 0; i < strs[0].length(); i++) {
            for (int j = 1; j < strs.length; j++) {
                if (strs[j].charAt(i) < strs[j - 1].charAt(i)) {
                    count++;
                    break;
                }
            }
        }
        return count;
    }
}

This site is open source. Improve this page.