/** ##Two to One Take 2 strings s1 and s2 including only letters from ato z. Return a new sorted string, the longest possible, containing distinct letters, each taken only once - coming from s1 or s2. a = "xyaabbbccccdefww" b = "xxxxyyyyabklmopq" longest(a, b) -> "abcdefklmopqwxy" a = "abcdefghijklmnopqrstuvwxyz" longest(a, a) -> "abcdefghijklmnopqrstuvwxyz" * @author changliu */ import static org.junit.Assert.*; import org.junit.Test; public class TwoToOne { public static char[] bubbleSort(char[] arr) { boolean swap = true; while(swap) { // initial state to be false, if no swap then it's stable swap = false; for (int i = 0; i < arr.length - 1; i++) { // if swapped, marked as true, since it may need further swap if (arr[i] > arr[i + 1]) { char tmp = arr[i]; arr[i] = arr[i + 1]; arr[i + 1] = tmp; swap = true; } } } return arr; } public static String longest(String a, String b) { String result = ""; for (int i = 0; i < a.length(); i++) { char s = a.charAt(i); /** * very trivial for debugging, here cannot use String.contains(s) * directly, as it requires CharSequence Use String.contains(""+s), * since String has CharSequence interface or Use * String.contains(String.toString(s)) instead. Very Important! You * don't know the details of the API, that's sooooooo bad! */ if (!result.contains("" + s)) { result += s; } } for (int j = 0; j < b.length(); j++) { char s = b.charAt(j); if (!result.contains("" + s)) { result += s; } } // Why here I cannot use test.toString() to return??? return new String(bubbleSort(result.toCharArray())); } @Test public void test() { System.out.println("longest Fixed Tests"); assertEquals("aehrsty", TwoToOne.longest("aretheyhere", "yestheyarehere")); assertEquals("abcdefghilnoprstu", TwoToOne.longest("loopingisfunbutdangerous", "lessdangerousthancoding")); assertEquals("acefghilmnoprstuy", TwoToOne.longest("inmanylanguages", "theresapairoffunctions")); } public static void main(String[] args) { new TwoToOne().test(); } }