859. Buddy Strings

Given two strings A and B of lowercase letters, return true if you can swap two letters inA so the result is equal toB , otherwise, returnfalse .

Swapping letters is defined as taking two indices i and j (0-indexed) such that i != j and swapping the characters at A[i] and A[j]. For example, swapping at indices 0 and 2 in "abcd" results in "cbad".

Example 1:

Input: A = "ab", B = "ba"
Output: true
**Explanation** **:** You can swap A[0] = 'a' and A[1] = 'b' to get "ba", which is equal to B.

Example 2:

Input: A = "ab", B = "ab"
Output: false
**Explanation** **:** The only letters you can swap are A[0] = 'a' and A[1] = 'b', which results in "ba" != B.

Example 3:

Input: A = "aa", B = "aa"
Output: true
**Explanation** **:** You can swap A[0] = 'a' and A[1] = 'a' to get "aa", which is equal to B.

Example 4:

Input: A = "aaaaaaabc", B = "aaaaaaacb"
Output: true

Example 5:

Input: A = "", B = "aa"
Output: false

Constraints:

• 0 <= A.length <= 20000
• 0 <= B.length <= 20000
• A and B consist of lowercase letters.

# @lc code=start
using LeetCode

function buddy_strings(A::String, B::String)::Bool
    if length(A) == length(B)
        different_pairs = Pair{Char,Char}[]
        for (a, b) in zip(A, B)
            if a != b
                push!(different_pairs, a => b)
            end
        end
        if length(different_pairs) == 0
            # check if A contains at least 2 duplicate letters
            length(Set(A)) < length(A)
        elseif length(different_pairs) == 2
            ((x, y), (z, w)) = different_pairs
            x == w && y == z
        else
            false
        end
    else
        false
    end
end
# @lc code=end

buddy_strings (generic function with 1 method)

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