How do you solve Increasing Decreasing String on LeetCode?

Increasing Decreasing String (LeetCode #1370) can be solved using Brute Force. The optimal approach is Brute Force with undefined time complexity and undefined space complexity. Key insight: The brute force approach involves repeatedly finding the smallest and largest characters in the string, appending them to the result, and removing them from the original string. This is simple but inefficient due to repeated searches.

What is the time complexity of Increasing Decreasing String?

The optimal solution for Increasing Decreasing String runs in undefined time and uses undefined space. undefined

What algorithm or data structure is used to solve Increasing Decreasing String?

Increasing Decreasing String uses the following concepts: Hash Table, String, Counting. The recommended patterns to study are: .

#1370

Increasing Decreasing String

Easy

Hash TableStringCounting

LeetCode ↗

Approaches

💡

Intuition

Time Space

The brute force approach involves repeatedly finding the smallest and largest characters in the string, appending them to the result, and removing them from the original string. This is simple but inefficient due to repeated searches.

⚙️

Algorithm

6 steps

1Step 1: Initialize an empty result string.
2Step 2: While there are characters left in the string, find and append the smallest character to the result.
3Step 3: Continue to find and append the next smallest character greater than the last appended character.
4Step 4: Once no more characters can be appended, find and append the largest character.
5Step 5: Continue to find and append the next largest character smaller than the last appended character.
6Step 6: Repeat steps 2-5 until all characters are processed.

solution.py18 lines

1def increasingDecreasingString(s):
2    result = ''
3    while s:
4        smallest = min(s)
5        result += smallest
6        s = s.replace(smallest, '', 1)
7        while s and (next_smallest := min(c for c in s if c > smallest)):
8            result += next_smallest
9            s = s.replace(next_smallest, '', 1)
10        if not s:
11            break
12        largest = max(s)
13        result += largest
14        s = s.replace(largest, '', 1)
15        while s and (next_largest := max(c for c in s if c < largest)):
16            result += next_largest
17            s = s.replace(next_largest, '', 1)
18    return result

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.