标签：class linked dig date har oid letter add string
Given a digit string, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on the telephone buttons) is given below. Input:Digit string "23" Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"]. Note: Although the above answer is in lexicographical order, your answer could be in any order you want.
临时容器 可以是"", 结果容器, 位置, cadidates[],
此题考察要递归和遍历的地方, 要遍历的容器在变
private static final String[] KEYS = { "", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz" };
public List<String> letterCombinations(String digits) {
List<String> ret = new LinkedList<String>();
if (digits == null || digits.length() == 0) return ret;
combination("", digits, 0, ret);
return ret;
}
private void combination(String prefix, String digits, int offset, List<String> ret) {
if (offset >= digits.length()) {
ret.add(prefix);
return;
}
String letters = KEYS[(digits.charAt(offset) - ‘0‘)]; //不断变化的, charAt() – ‘0’表示数组的位置
for (int i = 0; i < letters.length(); i++) {
combination(prefix + letters.charAt(i), digits, offset + 1, ret);
}
}
String letters = KEYS[(digits.charAt(offset) - ‘0‘)]; //不断变化的, charAt() – ‘0’表示数组的位置
17. Letter Combinations of a Phone Number
标签：class linked dig date har oid letter add string
原文地址：http://www.cnblogs.com/apanda009/p/7236382.html
