Sponsored
Sponsored
This approach involves a straightforward comparison between the two strings. First, check if both strings are equal in length. If not, return false immediately. Next, identify the indices where the two strings differ. If there are exactly two such indices and swapping these characters in the first string can make it identical to the second, return true. Additionally, handle the edge case where both strings are already identical but contain at least one character that repeats, in which case a swap is possible and returns true.
Time Complexity: O(n), as we traverse the strings with a single pass to gather differences.
Space Complexity: O(1) for constant-space operations, though storing differences requires space proportional to the number of differences.
1def buddyStrings(s: str, goal: str) -> bool:
2 if len(s) != len(goal):
3 return False
4 if s == goal:
5 return len(set(s)) < len(s)
6 diff = [(a, b) for a, b in zip(s, goal) if a != b]
7 return len(diff) == 2 and diff[0] == diff[1][::-1]The function first checks if the strings are of different lengths, returning false immediately. It then handles the case when both strings are identical by checking for repeated characters using a set, since a swap is impossible without repetition. For differing strings, it constructs a list of differing positions. If there are exactly two differences and swapping them resolves equality, the function returns true.
This alternative method relies on character frequency counts and permutation verifications. If the strings differ in length, they're immediately ruled out. By evaluating how character frequencies align and applying permutation checks, the function can discern valid swaps that potentially achieve the goal formation of the strings.
Time Complexity: O(n), scanning all potential indices to locate and evaluate differences.
Space Complexity: O(n) theoretically with list storage though practically controlled by processing mechanism constraints.
1import java.util.*;
2
The Java Solution uses ArrayList to store differing indices while also handling special cases for direct equality and duplication presence. It'll iterate through the string, populating discrepancies only to check their viability for a simple swap.