Introduction

In this blog post, we will explore how to solve the LeetCode problem "228" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

You are given a sorted unique integer array nums. A range [a,b] is the set of all integers from a to b (inclusive). Return the smallest sorted list of ranges that cover all the numbers in the array exactly. That is, each element of nums is covered by exactly one of the ranges, and there is no integer x such that x is in one of the ranges but not in nums. Each range [a,b] in the list should be output as: "a->b" if a != b "a" if a == b Example 1: Input: nums = [0,1,2,4,5,7] Output: ["0->2","4->5","7"] Explanation: The ranges are: [0,2] --> "0->2" [4,5] --> "4->5" [7,7] --> "7" Example 2: Input: nums = [0,2,3,4,6,8,9] Output: ["0","2->4","6","8->9"] Explanation: The ranges are: [0,0] --> "0" [2,4] --> "2->4" [6,6] --> "6" [8,9] --> "8->9" Constraints: 0 <= nums.length <= 20 -231 <= nums[i] <= 231 - 1 All the values of nums are unique. nums is sorted in ascending order.

Explanation

• Iterate through the sorted array, identifying the start and end of each range.
  • If the current element is not consecutive to the previous one, a new range begins.
  • Format the range as "a->b" if the start and end are different, or "a" if they are the same.

• Runtime Complexity: O(n), Storage Complexity: O(n)

Code

    def summaryRanges(nums):
    """
    You are given a sorted unique integer array nums.
    A range [a,b] is the set of all integers from a to b (inclusive).
    Return the smallest sorted list of ranges that cover all the numbers in the array exactly.
    That is, each element of nums is covered by exactly one of the ranges,
    and there is no integer x such that x is in one of the ranges but not in nums.
    Each range [a,b] in the list should be output as:
    "a->b" if a != b
    "a" if a == b

    Example 1:
    Input: nums = [0,1,2,4,5,7]
    Output: ["0->2","4->5","7"]
    Explanation: The ranges are:
    [0,2] --> "0->2"
    [4,5] --> "4->5"
    [7,7] --> "7"

    Example 2:
    Input: nums = [0,2,3,4,6,8,9]
    Output: ["0","2->4","6","8->9"]
    Explanation: The ranges are:
    [0,0] --> "0"
    [2,4] --> "2->4"
    [6,6] --> "6"
    [8,9] --> "8->9"

    Constraints:
    0 <= nums.length <= 20
    -231 <= nums[i] <= 231 - 1
    All the values of nums are unique.
    nums is sorted in ascending order.
    """
    ranges = []
    if not nums:
        return ranges

    start = nums[0]
    end = nums[0]

    for i in range(1, len(nums)):
        if nums[i] == end + 1:
            end = nums[i]
        else:
            if start == end:
                ranges.append(str(start))
            else:
                ranges.append(str(start) + "->" + str(end))
            start = nums[i]
            end = nums[i]

    if start == end:
        ranges.append(str(start))
    else:
        ranges.append(str(start) + "->" + str(end))

    return ranges