LeetCode Entry

1331. Rank Transform of an Array

12.07.2026 easy 2026 kotlin rust

Rank of items in an array

1331. Rank Transform of an Array easy substack youtube

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Problem TLDR

Rank of items in an array

Intuition

Sort. Dedup. Binary search each number.

Approach

• we can use toSortedMap().run { … headSet(it).size } but leetcode give TLE, still O(nlogn)
• Rust: use itertools and collect tuples to the hashmap

Complexity

• Time complexity: \(O(nlogn)\)

• Space complexity: \(O(n)\)

Code

    fun arrayRankTransform(a: IntArray) =
    a.toSet().sorted().run { a.map { binarySearch(it) + 1 } }

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