859. Buddy Strings

Given two strings A and B of lowercase letters, return true if and only if we can swap two letters in A so that the result equals B.Example 1:Input: A = “ab”, B = “ba"Output: trueExample 2:Input: A = “ab”, B = “ab"Output: falseExample 3:Input: A = “aa”, B = “aa"Output: trueExample 4:Input: A = “aaaaaaabc”, B = “aaaaaaacb"Output: trueExample 5:Input: A = “”, B = “aa"Output: falseNote:0 <= A.length <= 200000 <= B.length <= 20000A and B consist only of lowercase letters.难度: Medium题目：给定两字符串Ａ和Ｂ且由小写字线组成，返回ＡＢ是否由仅交换两个字符可以相互生成。思路：判断长度，记录不同位置的个数，记录是否有相同的字符。Runtime: 3 ms, faster than 81.94% of Java online submissions for Buddy Strings.Memory Usage: 38.6 MB, less than 50.00% of Java online submissions for Buddy Strings.class Solution { public boolean buddyStrings(String A, String B) { if (A.length() != B.length()) { return false; } int[] tableA = new int[26]; int[] tableB = new int[26]; int diffPosition = 0; for (int i = 0; i < A.length(); i++) { char a = A.charAt(i); char b = B.charAt(i); if (a != b) { diffPosition++; } if (diffPosition > 2) { return false; } tableA[a - ‘a’]++; tableB[b - ‘a’]++; } boolean duplicated = false; for (int i = 0; !duplicated && i < 26; i++) { if (tableA[i] != tableB[i]) { return false; } duplicated = tableA[i] > 1 ? !duplicated : duplicated; } return 2 == diffPosition || duplicated; }}