s1 is equal to s2, return true as no swap is needed.diff to store indices where s1 and s2 differ.s1 and s2:
a. If the characters at the current index are different, add the index to diff.diff is not 2, return false as we can't make the strings equal with one swap.diff would make the strings equal:
a. If s1[diff[0]] == s2[diff[1]] and s1[diff[1]] == s2[diff[0]], return true.
b. Otherwise, return false.