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package middle;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class 电话号码组合 {
public static void main(String[] args) {
String str = "273";
List<String> list = letterCombinations(str);
System.out.println(list);
}
public static List<String> letterCombinations(String digits) {
List<String> list = new ArrayList<>();
Map<Character, String> map = new HashMap<Character, String>();
map.put('2', "abc");
map.put('3', "def");
map.put('4', "ghi");
map.put('5', "jkl");
map.put('6', "mno");
map.put('7', "pqrs");
map.put('8', "tuv");
map.put('9', "wxyz");
method(map, list, digits, "");
return list;
}
/**
*
* @param map
* 按键映射
* @param list
* 最终链表
* @param s
* 当前输入的数字字符
* @param result
* 中转字符，起始为空字符
*/
public static void method(Map<Character, String> map, List<String> list, String s, String result) {
if (s == "") {
return;
}
String str = map.get(s.charAt(0));
for (int i = 0; i < str.length(); i++) {
String result2 = result + str.charAt(i);
if (s.length() > 1) {
method(map, list, s.substring(1), result2);
} else if (s.length() == 1) {
list.add(result2);
}
}
}
}
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