LeetCode17 Done

[jhm9595]

Time Complexity : O(N...)?

[bigelephant29]

Usually for this kind of objects we'll make it a static object and construct it within a static class.

The reason is that you'll probably be able to reuse the same object at many places but apparently you don't want to construct it again and again.

[bigelephant29]

String[] str = new String[digits.length()];

You don't need the variable digitsLength.

digits.length() is very trivial and straightforward.

[bigelephant29]

Take a look into this snippet, I wrote this based on your code:

class Solution {
	public List<String> letterCombinations(String digits) {
		
		List<String> list = new ArrayList<String>();
		
		if(digits.isEmpty()) return list;
		
		Map<Integer, String> digitMap = new HashMap<Integer, String>();
		
		digitMap.put(2, "abc");
		digitMap.put(3, "def");
		digitMap.put(4, "ghi");
		digitMap.put(5, "jkl");
		digitMap.put(6, "mno");
		digitMap.put(7, "pqrs");
		digitMap.put(8, "tuv");
		digitMap.put(9, "wxyz");
		
		int digitsLength = digits.length();
		
		list.add("");
        
		for(int i = 0; i < digits.length(); i++) {
			String words = digitMap.get(Integer.valueOf(String.valueOf(digits.charAt(i))));

			List<String> newList = new ArrayList<String>();
			for(String s: list) {
				for(char c: words.toCharArray()) {
					newList.add(s+c);
				}
			}
			list = newList;
		}

		return list;
	}
}

[jhm9595]

Wow. This make me overwhelmed.
So brilliant! Thank you.