Sponsored
Sponsored
In this approach, we use the property that a rotated version of a string s can be found as a substring of s + s. This is because rotating doesn't change the length of the string and by concatenating the string to itself, every possible rotation is covered.
Time Complexity: O(n^2), where n is the length of the string, due to using strstr.
Space Complexity: O(n), for the doubled string.
1def rotateString(s: str, goal: str) -> bool:
2 if len(s) != len(goal):
3 return False
4 return goal in (s + s)For the Python solution, we first compare the lengths of s and goal. If they're unequal, we return False. Otherwise, we check if goal is a substring of the concatenated string s + s.
This approach simulates rotating the string s multiple times (equal to its length) to check if it equals goal at any point. This is a straightforward but less efficient method compared to the concatenation method.
Time Complexity: O(n^2), because we check for each possible rotation of s for a match with goal.
Space Complexity: O(1), as no additional storage is used beyond some counters.
1 public bool RotateString(string s, string goal) {
if (s.Length != goal.Length) return false;
int len = s.Length;
for (int i = 0; i < len; i++) {
string rotated = s.Substring(i) + s.Substring(0, i);
if (rotated.Equals(goal)) return true;
}
return false;
}
}In this C# implementation, each iteration generates a new rotation by slicing and concatenating parts of s, and checks if it equals goal.