Introduction

In this blog post, we will explore how to solve the LeetCode problem "899" 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 string s and an integer k. You can choose one of the first k letters of s and append it at the end of the string. Return the lexicographically smallest string you could have after applying the mentioned step any number of moves. Example 1: Input: s = "cba", k = 1 Output: "acb" Explanation: In the first move, we move the 1st character 'c' to the end, obtaining the string "bac". In the second move, we move the 1st character 'b' to the end, obtaining the final result "acb". Example 2: Input: s = "baaca", k = 3 Output: "aaabc" Explanation: In the first move, we move the 1st character 'b' to the end, obtaining the string "aacab". In the second move, we move the 3rd character 'c' to the end, obtaining the final result "aaabc". Constraints: 1 <= k <= s.length <= 1000 s consist of lowercase English letters.

Explanation

Here's the breakdown of the approach, complexity, and Python code:

• Key Approach:

  • If k > 1, we can bring any character to the front through a series of moves. Effectively, we can sort the string.
  • If k == 1, we repeatedly move the first character to the end and keep track of the lexicographically smallest string encountered.

• Complexity:

  • Time Complexity: O(n log n) if k > 1, O(n^2) if k = 1, where n is the length of the string.
  • Space Complexity: O(n)

Code

    def solve():
    s = input()
    k = int(input())

    if k > 1:
        return "".join(sorted(s))
    else:
        best = s
        for _ in range(len(s)):
            s = s[1:] + s[0]
            if s < best:
                best = s
        return best

print(solve())