Time Complexity · #32 · 2026-05-06

What's the Big-O?

Go ·Difficulty 1/3

How to play

Read the code and pick its time complexity from four Big-O choices. Think about loops, recursion, and hidden costs. Press 1–4 or click to answer.

n = len(nums). What is the average-case time complexity?

package main

func twoSum(nums []int, target int) [2]int {
    seen := make(map[int]int)
    for i, v := range nums {
        if j, ok := seen[target-v]; ok {
            return [2]int{j, i}
        }
        seen[v] = i
    }
    return [2]int{-1, -1}
}

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Press 1 through 4, or tap a numbered choice, to answer. Back to hub