LeetCode Entry

944. Delete Columns to Make Sorted

20.12.2025 easy 2025 kotlin rust

Count unsorted columns

944. Delete Columns to Make Sorted easy blog post substack youtube

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Problem TLDR

Count unsorted columns #easy

Intuition

Compare column with its sorted variant.

Approach

• or compare adjucent rows in a column

Complexity

• Time complexity: \(O(nm)\) or nmlogn

• Space complexity: \(O(n)\) or O(1)

Code

// 84ms
    fun minDeletionSize(s: Array<String>) =
        s[0].indices.map{i -> s.map{it[i]}}.count { it != it.sorted() }

// 1ms
    pub fn min_deletion_size(s: Vec<String>) -> i32 {
        (0..s[0].len()).filter(|&i| (1..s.len()).any(|j| s[j-1].as_bytes()[i]>s[j].as_bytes()[i])).count() as _