LeetCode Entry

154. Find Minimum in Rotated Sorted Array II

16.05.2026 hard 2026 kotlin rust

Binary search in shifted array with duplicates

154. Find Minimum in Rotated Sorted Array II hard substack youtube

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Problem TLDR

Binary search in shifted array with duplicates

Intuition

    // 3 4 5 6 7 1 2 3
    // 3 1
    // false false
    // 3 1 3
    // false true false

• compare all elements with last
• slice duplicates out in O(N)

Approach

• use built-in functions, Rust: partition_point, position, slices [..], Kotlin: binarySearch {..}, indexOfFirst
• x.inv() is -1-x

Complexity

• Time complexity: \(O(n|logn)\)

• Space complexity: \(O(1)\)

Code

    fun findMin(n: IntArray) = n[n.asList().binarySearch(
        max(0, n.indexOfFirst { it != n.last()})) {
            if (it <= n.last()) 1 else -1 }.inv()]

    pub fn find_min(n: Vec<i32>) -> i32 {
        let n = &n[n.iter().position(|&x| x != n[n.len()-1]).unwrap_or(0)..];
        n[n.partition_point(|&x|x > n[n.len()-1])]
    }