leetcode17. letter combinations of a phone number

输出电话号码能表示出的所有字符串。

17. Letter Combinations of a Phone Number

Given a string containing digits from 2-9 inclusive, 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. Note that 1 does not map to any letters.

Example:

1 2	Input: "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.

算法：字符的全组合

这道题的难点是理解题意，设计循环的执行方案。

private String[] digitLetters = {"","","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
public List<String> (String digits) {
    if (digits.length() == 0) return new ArrayList<>();
    List<String> ans = new ArrayList<>();
    ans.add("");
    for (int i = 0; i < digits.length(); i++) {
        ans = combine(ans, digitLetters[digits.charAt(i) - '0']);
    }
    return ans;
}
public List<String> combine(List<String> ans, String str) {
    List<String> res = new ArrayList<>();
    for (String s : ans) {
        for (int i = 0; i < str.length(); i++) {
            res.add(s + str.charAt(i));
        }
    }
    return res;
}

leetcode17. letter combinations of a phone number

17. Letter Combinations of a Phone Number

算法：字符的全组合

近期文章

近期评论

标签

热门

文章归档

分类目录

功能