leetcode/code/lc17.java at master · mJackie/leetcode · GitHub

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package code;

import java.util.List;

import java.util.Vector;

* 17. Letter Combinations of a Phone Number

* 题意：手机键盘字母输入

* 难度：Medium

* 思路：思路记一下，每次放到vector中，遍历vector,加上所有的可能

* 分类：String, Backtracking

public class lc17 {

public static void main(String[] args) {

System.out.println(letterCombinations("23").toString());

}

public static List<String> letterCombinations(String digits) {

Vector<String> res = new Vector<>();

if(digits.length()==0)

return res;

String[] charmap = {"","","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};

res.add("");

for (int i = 0; i < digits.length(); i++) {

int n = digits.charAt(i)-'0';

Vector<String> temp_res = new Vector<>();

for (int j = 0; j < charmap[n].length(); j++) {

for (int k = 0; k < res.size(); k++) {

temp_res.add(res.get(k)+charmap[n].charAt(j));

}

res = temp_res;

}

return res;

}

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