Is Missing Ranges easy or hard?

Missing Ranges is classified as an Easy problem. The challenge lies in handling edge cases such as gaps at the beginning or end of the range and formatting single-number ranges versus multi-number ranges correctly.

How to solve Missing Ranges in O(n)?

Initialize a variable such as prev = lower - 1 and iterate through the array, treating upper + 1 as a final sentinel. For each number curr, check if curr - prev > 1. When the condition holds, record the range [prev + 1, curr - 1]. Update prev to curr and continue scanning.

What is the best approach for Missing Ranges?

The most efficient approach is a linear scan simulation that detects gaps between consecutive values. Track the previous number and compare it with the current number in the sorted array. Whenever the difference is greater than one, a missing range exists. This method runs in O(n) time with O(1) extra space.

What data structure is used in Missing Ranges?

The problem primarily uses arrays and simple integer variables for boundary tracking. No complex data structures are required. The algorithm relies on comparing consecutive values and storing resulting ranges in a list.

What is the time complexity of Missing Ranges?

The optimal solution runs in O(n) time where n is the number of elements in the array. The algorithm performs a single pass and checks the gap between adjacent numbers. Space complexity is O(1) excluding the output list of ranges.

Missing Ranges Python or Java solution approach?

Both Python and Java implementations follow the same logic: iterate through the array, track the previous value, and append missing intervals when a gap is detected. The solution maintains O(n) time complexity and constant auxiliary space regardless of language.

Is Missing Ranges asked at Google, Amazon, or Meta?

Missing Ranges appears in interview preparation sets for companies like Google and Meta because it tests array traversal, boundary handling, and edge cases. The problem evaluates whether candidates can detect intervals efficiently using a single pass over sorted data.

Description Solution Video 7:07

163. Missing Ranges

Easy35.5% acceptance2 companiesPremium elsewhere, free here

You are given an inclusive range [lower, upper] and a sorted unique integer array nums, where all elements are within the inclusive range.

A number x is considered missing if x is in the range [lower, upper] and x is not in nums.

Return the shortest sorted list of ranges that exactly covers all the missing numbers. That is, no element of nums is included in any of the ranges, and each missing number is covered by one of the ranges.

Example 1:

Input: nums = [0,1,3,50,75], lower = 0, upper = 99
Output: [[2,2],[4,49],[51,74],[76,99]]
Explanation: The ranges are:
[2,2]
[4,49]
[51,74]
[76,99]

Example 2:

Input: nums = [-1], lower = -1, upper = -1
Output: []
Explanation: There are no missing ranges since there are no missing numbers.

Constraints:

-10⁹ <= lower <= upper <= 10⁹
0 <= nums.length <= 100
lower <= nums[i] <= upper
All the values of nums are unique.

Asked at 2 companies

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Array

7:07

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163. Missing Ranges

Asked at 2 companies

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