Given two strings: s1
and s2
with the same size, check if some permutation of string s1
can break some permutation of string s2
or vice-versa. In other words s2
can break s1
or vice-versa.
A string x
can break string y
(both of size n
) if x[i] >= y[i]
(in alphabetical order) for all i
between 0
and n-1
.
Example 1:
Input: s1 = "abc", s2 = "xya" Output: true Explanation: "ayx" is a permutation of s2="xya" which can break to string "abc" which is a permutation of s1="abc".
Example 2:
Input: s1 = "abe", s2 = "acd" Output: false Explanation: All permutations for s1="abe" are: "abe", "aeb", "bae", "bea", "eab" and "eba" and all permutation for s2="acd" are: "acd", "adc", "cad", "cda", "dac" and "dca". However, there is not any permutation from s1 which can break some permutation from s2 and vice-versa.
Example 3:
Input: s1 = "leetcodee", s2 = "interview" Output: true
Constraints:
s1.length == n
s2.length == n
1 <= n <= 10^5
This problem asks whether one string's permutation can lexicographically dominate another string's permutation. The solution leverages the fact that sorting the strings allows for a straightforward comparison.
Approach:
Sort: Sort both input strings s1
and s2
alphabetically. This ensures that we're comparing the strings in their lexicographically "best" possible forms.
Check Domination: We need to check if one sorted string dominates the other (meaning every character in one string is greater than or equal to the corresponding character in the other). This is done twice: once for s1
potentially dominating s2
, and once for s2
potentially dominating s1
.
Return: The function returns true
if either domination condition is met, indicating that a permutation of one string can break a permutation of the other. Otherwise, it returns false
.
Time Complexity Analysis:
check
function (comparing the sorted strings) takes O(N) time.Therefore, the overall time complexity of the solution is O(N log N), dominated by the sorting step.
Space Complexity Analysis:
The space complexity is O(N) in the worst case because we are creating sorted copies of the input strings in some implementations. In some languages like C++, the sort
function may perform in-place sorting, reducing space complexity to O(1) in those cases. However, O(N) is a safe upper bound for space complexity.
The Python code is concise and directly implements the approach:
class Solution:
def checkIfCanBreak(self, s1: str, s2: str) -> bool:
cs1 = sorted(s1) # Sort s1
cs2 = sorted(s2) # Sort s2
return all(a >= b for a, b in zip(cs1, cs2)) or all( # Check if s1 dominates s2 or vice-versa
a <= b for a, b in zip(cs1, cs2)
)
zip(cs1, cs2)
efficiently iterates through both sorted strings simultaneously. all(...)
ensures that all pairwise comparisons satisfy the condition (greater than or equal to, or less than or equal to). The or
combines both domination checks.
The code in Java, C++, Go, and TypeScript follows the same algorithmic approach. The differences primarily lie in syntax and how sorting and character array handling are implemented in each language. For example:
Arrays.sort()
for sorting and iterates with a for
loop and explicit array index access.std::sort()
for sorting and iterates with a for
loop and explicit array index access.sort.Slice()
which requires a custom comparison function for sorting byte slices. Uses a nested function for better code organization.Array.from()
to convert strings to arrays, .sort()
for sorting, and for
loops.All the implementations, however, maintain the same core logic of sorting and comparing the strings to determine if one can break the other.