Letter Combinations of a Phone Number 2021-05-31 19:00
public static List<String> letterCombinations(String digits) {
Map<Character, List<String>> map = new HashMap<>();
map.put('2', Arrays.asList("a", "b", "c"));
map.put('3', Arrays.asList("d", "e", "f"));
map.put('4', Arrays.asList("g", "h", "i"));
map.put('5', Arrays.asList("j", "k", "l"));
map.put('6', Arrays.asList("m", "n", "o"));
map.put('7', Arrays.asList("p", "q", "r", "s"));
map.put('8', Arrays.asList("t", "u", "v"));
map.put('9', Arrays.asList("w", "x", "y", "z"));
List<String> res = new LinkedList<>();
for (Character c : digits.toCharArray()) {
List<String> curStr = map.get(c);
if (res.size() == 0) {
res.addAll(curStr);
}else{
List<String> newRes = new LinkedList<>();
for(String existCharacter:res){
for(String cur:curStr){
newRes.add(existCharacter+cur);
res = newRes;
}
}
}
}
return res;
}
| Runtime | Memory |
|---|---|
| 1 ms | 37.7 MB |
EOF