求第一个无重复字符,如"total"的第一个无重复字符是o,"teeter"的第一个无重复字符是r,效率要优于O(n的平方)
public static Character FirstNonRepeated(String)
------解决方案--------------------
都是ascii字符的话比较简单，O(n)就可以了
- Java code
public static Character FirstNonRepeated(String string) { int[] counter = new int[128]; for (int i = 0; i < string.length(); i++) { char ch = string.charAt(i); counter[ch]++;; } for (int i = 0; i < string.length(); i++) { char ch = string.charAt(i); if(counter[ch] == 1) return ch; } return null; }