Algorithm:
Count the number of occurrence of each character.
Only one character with odd occurrence is allowed since in a palindrome maximum number of character with odd occurrence can be ‘1‘.
All other character should occur in even number of times.
If (2) and (3) fail, then the given string is not a palindrome.
1 public int check(String str) { 2 HashMap<Character, Integer> map = new HashMap<Character, Integer>(); 3 for (int i=0; i<str.length(); i++) { 4 char c = str.charAt(i); 5 if (map.containsKey(c)) { 6 map.put(c, map.get(c)+1); 7 } 8 else { 9 map.put(c, 1); 10 } 11 } 12 13 int cntOdd = 0; 14 for (int val : map.values()) { 15 if (val % 2 == 1) { 16 cntOdd++; 17 } 18 } 19 return cntOdd>1? 0 : 1; 20 }
Twitter OA prepare: Anagram is A Palindrome
原文：http://www.cnblogs.com/EdwardLiu/p/4323200.html