161. One-Edit-Distance

class Solution:
    """
    @param s: a string
    @param t: a string
    @return: true if they are both one edit distance apart or false
    """
    def is_one_edit_distance(self, s: str, t: str) -> bool:
        # write your code here
        m = len(s)
        n = len(t)
        if abs(m-n) > 1:
            return False;
        if m > n:
            m, n = n, m
            s, t = t, s
        
        for i in range(m):
            if s[i] != t[i]:
                if m == n:
                    return s[i+1:] == t[i+1:]
                else:
                    return s[i:] == t[i+1:]

        return m + 1 == n