Java one pass || O(N) - O(1)
\n\n\t    int swap = 0;\n\t\tint a = 0;\n\t\tint b = 0;\n\t\t\n\t\tfor(int i = 0; i < s1.length() &&  swap < 2 ; i++)\n\t\t{\n\t\t\tint x = s1.charAt(i);\n\t\t\
\n```\n\t    int swap = 0;\n\t\tint a = 0;\n\t\tint b = 0;\n\t\t\n\t\tfor(int i = 0; i < s1.length() &&  swap < 2 ; i++)\n\t\t{\n\t\t\tint x = s1.charAt(i);\n\t\t\tint y = s2.charAt(i);\n\t\t\t\n\t\t\tif (a == y && b == x) {\n\t\t\t\ta = 0;\n\t\t\t\tb = 0;\n\t\t\t}\n\t\t\telse if (x != y) {\n\t\t\t\tswap++;\n\t\t\t\ta = x;\n\t\t\t\tb = y;\n\t\t\t}\n\t\t}\n\t\treturn a+b == 0 && swap < 2;\n```
['Java']