@@ -0,0 +1,270 @@
+// http://codingbat.com/prob/p107259// %0A%0Apublic Map%3CString, String%3E mapAB(Map%3CString, String%3E map) %7B%0A  boolean bothKeysPresent = (map.containsKey(%22a%22) && map.containsKey(%22b%22));%0A  if (bothKeysPresent) %7B%0A    map.put(%22ab%22, map.get(%22a%22) + map.get(%22b%22));%0A  %7D%0A  return map;%0A%7D%0A

Create mapAB.java