EasyNo. 1790
Check if One String Swap Can Make Strings Equal — LeetCode 1790 Python Solution
- Pattern
- Hash Map
- Topics
- Hash Table, String, Counting
- Reading time
- 2 min
- Source
- leetcode.com
The problem
You are given two strings s1 and s2 of equal length. A string swap is an operation where you choose two indices in a string (not necessarily different) and swap the characters at these indices.
Example
- Input
- s1 = "bank", s2 = "kanb"
- Output
- true
- Explanation
- For example, swap the first character with the last character of s2 to make "bank".
Python solution
class Solution:
def areAlmostEqual(self, s1: str, s2: str) -> bool:
cnt = 0
c1 = c2 = None
for a, b in zip(s1, s2):
if a != b:
cnt += 1
if cnt > 2 or (cnt == 2 and (a != c2 or b != c1)):
return False
c1, c2 = a, b
return cnt != 1Complexity
- Time
- O(n)where n is the length of the string
- Space · auxiliary
- O(1)
Pattern: Hash Map
Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1790. Check if One String Swap Can Make Strings Equal is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table and Counting.
The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.
Related problems
| No. | Problem | Difficulty |
|---|---|---|
| 1781 | Sum of Beauty of All Substrings | Medium |
| 0299 | Bulls and Cows | Medium |
| 0383 | Ransom Note | Easy |
| 0387 | First Unique Character in a String | Easy |
| 0451 | Sort Characters By Frequency | Medium |
| 0692 | Top K Frequent Words | Medium |
Frequently asked questions
- How hard is LeetCode 1790. Check if One String Swap Can Make Strings Equal?
LeetCode 1790. Check if One String Swap Can Make Strings Equal is rated Easy on LeetCode.
- What is the time complexity of LeetCode 1790. Check if One String Swap Can Make Strings Equal?
The Python solution on this page runs in O(n), where n is the length of the string.
- What is the space complexity of LeetCode 1790. Check if One String Swap Can Make Strings Equal?
The Python solution on this page uses O(1) auxiliary space.
- What topics does LeetCode 1790. Check if One String Swap Can Make Strings Equal cover?
LeetCode 1790. Check if One String Swap Can Make Strings Equal is tagged Hash Table, String and Counting on LeetCode.