Write a function that reads two input strings and returns true if they match exactly or if they can be made equal by swapping exactly one pair of characters in one of the strings; otherwise return false.

The solution is identical to the one described for question 1. First verify that the strings have the same length. Then scan both strings simultaneously, collecting the indices where the characters differ. If there are no differences, the strings are already equal, so return true. If there are exactly two differences, check that swapping the two mismatched characters in one string would align the strings: the character at the first mismatch in the first string must equal the character at the second mismatch in the second string, and vice versa. If this holds, return true; otherwise return false. Any other number of mismatches (one or more than two) means a single swap cannot reconcile the strings, so return false. The algorithm runs in linear time O(n) and uses constant extra space.