leetcode/Problem17.java at master · actor168/leetcode · GitHub

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importjava.util.*;

classProblem17 {
publicstaticvoidmain(String[] args) {
System.out.println(newProblem17().letterCombinations("9"));
	}

publicList<String> letterCombinations(Stringdigits) {
List<String> res = newArrayList<>();
if (digits.length() ==0) returnres;

charc = digits.charAt(0);
char[] arr = null;
charpos = (char)('a' + 3 * (c-'2'));
if(c == '7' ) {
arr = newchar[]{(char)pos, (char)(pos+1), (char)(pos+2), (char)(pos+3)};
 }else
if(c == '8') {
arr = newchar[]{(char)(pos+1), (char)(pos+2), (char)(pos+3)};
 } else
if(c == '9') {
arr = newchar[]{(char)(pos+1), (char)(pos+2), (char)(pos+3),(char)(pos+4)};
 } elsearr = newchar[]{(char)pos, (char)(pos+1), (char)(pos+2)};

List<String> resSub = letterCombinations(digits.substring(1));
for (inti = 0; i < arr.length; i++) {
if(resSub.size() > 0) {
for (intj = 0; j < resSub.size(); j++) {
res.add(String.valueOf(arr[i]) + resSub.get(j));
 }
 } else {
res.add(String.valueOf(arr[i]));
 }
 }
returnres;
 }
}