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Copy pathPhoneNumber2.java
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40 lines (36 loc) · 1.19 KB
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package leetcode;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Created by helmeter on 6/13/16.
*/
public class PhoneNumber2 {
public List<String> letterCombinations(String digits) {
Map<Character, String> map = new HashMap<Character, String>(){{
put('2', "abc"); put('3', "def"); put('4', "ghi"); put('5', "jkl");
put('6', "mno"); put('7', "pqrs"); put('8', "tuv"); put('9', "wxyz");
}};
List<String> ret = new ArrayList<String>();
if (digits.equals("")) {
return ret;
}
dfs(digits, 0, "", map, ret);
return ret;
}
private void dfs(String digits, int idx, String path, Map<Character, String> map, List<String> ret) {
if (digits.length() == path.length()) {
ret.add(path);
return;
}
for (int i = idx; i < digits.length(); i++) {
for (char c: map.get(digits.charAt(i)).toCharArray()) {
dfs(digits, i+1, path+c, map, ret);
}
}
}
public static void main(String[] args) {
System.out.println(new PhoneNumber2().letterCombinations("237"));
}
}