Delete Columns to Make Sorted III

arraystringdynamic programming

Problem Statement

You are given an array of n strings strs , all of the same length.

We may choose any deletion indices, and we delete all the characters in those indices for each string.

For example, if we have strs = ["abcdef","uvwxyz"] and deletion indices {0, 2, 3} , then the final array after deletions is ["bef", "vyz"] .

Suppose we chose a set of deletion indices answer such that after deletions, the final array has every string (row) in lexicographic order. (i.e., (strs[0][0] <= strs[0][1] <= ... <= strs[0][strs[0].length - 1]) , and (strs[1][0] <= strs[1][1] <= ... <= strs[1][strs[1].length - 1]) , and so on). Return the minimum possible value of answer.length .

Examples

Example 1

Input: strs = ["babca","bbazb"]
Output: 3
After deleting columns 0, 1, and 4, the final array is strs = ["bc", "az"].
Both these rows are individually in lexicographic order (ie. strs[0][0] <= strs[0][1] and strs[1][0] <= strs[1][1]).
Note that strs[0] > strs[1] - the array strs is not necessarily in lexicographic order.

Example 2

Input: strs = ["edcba"]
Output: 4
If we delete less than 4 columns, the only row will not be lexicographically sorted.

Example 3

Input: strs = ["ghi","def","abc"]
Output: 0
All rows are already lexicographically sorted.

Constraints

n == strs.length

1 <= n <= 100

1 <= strs[i].length <= 100

strs[i] consists of lowercase English letters.

😤

Hard

Difficulty

Topic Info

ModuleDSA

CategoryArray

Sub-topicString