EasyNo. 1758
Minimum Changes To Make Alternating Binary String — LeetCode 1758 Python Solution
- Pattern
- Hash Map
- Topics
- String
- Reading time
- 2 min
- Source
- leetcode.com
The problem
You are given a string s consisting only of the characters '0' and '1'. In one operation, you can change any '0' to '1' or vice versa.
Example
- Input
- s = "0100"
- Output
- 1
- Explanation
- If you change the last character to '1', s will be "0101", which is alternating.
Python solution
class Solution:
def minOperations(self, s: str) -> int:
cnt = sum(c != '01'[i & 1] for i, c in enumerate(s))
return min(cnt, len(s) - cnt)Complexity
- Time
- O(n)
- Space · auxiliary
- O(1) to O(n)
Pattern: Hash Map
Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1758. Minimum Changes To Make Alternating Binary String is filed here because the reference solution below belongs to the algorithm family this hub collects, even though its LeetCode tags point elsewhere.
The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.
Related problems
| No. | Problem | Difficulty |
|---|---|---|
| 0006 | Zigzag Conversion | Medium |
| 0008 | String to Integer (atoi) | Medium |
| 0038 | Count and Say | Medium |
| 0058 | Length of Last Word | Easy |
| 0065 | Valid Number | Hard |
| 0068 | Text Justification | Hard |
Frequently asked questions
- How hard is LeetCode 1758. Minimum Changes To Make Alternating Binary String?
LeetCode 1758. Minimum Changes To Make Alternating Binary String is rated Easy on LeetCode.
- What topics does LeetCode 1758. Minimum Changes To Make Alternating Binary String cover?
LeetCode 1758. Minimum Changes To Make Alternating Binary String is tagged String on LeetCode.