Map - [Java]

for (Integer key : map.keySet()) {
			System.out.println("key : " + key + " value : " + map.get(key));
		}

for (Map.Entry<Integer, String> element : map.entrySet()) {
			System.out.println("key : " + element.getKey() + " value : " + element.getValue());
		}

Iterator<Integer> keys = map.keySet().iterator();
		while (keys.hasNext()) {
			Integer key = keys.next();
			System.out.println("key : " + key + " value : " + map.get(key));
		}

public class Q1 {

	public static void main(String[] args) {
		String s = "inflearninlove";

		System.out.println(solve(s));
	}

	public static int solve(String s) {

		if (s == null || s.length() == 0) {
			return -1;
		}

		Map<Character, Integer> map = new HashMap<Character, Integer>();

		for (char ch : s.toCharArray()) {
			// 1
			map.put(ch, map.getOrDefault(ch, 0) + 1);

			// 2
//			if (!map.containsKey(ch)) {
//				map.put(ch, 1);
//			} else {
//				map.put(ch, map.get(ch) + 1);
//			}
		}

		for (int i = 0; i < s.length(); i++) {
			if (map.get(s.charAt(i)) == 1) {
				return i;
			}
		}

		return -1;
	}

}

public class Q2 {

	public static void main(String[] args) {
		int[] nums = { 1, 1, 2, 2, 2, 2, 3, 5, 5, 5, 5 };
		int k = 2;

		System.out.println(solve(nums, k));
	}

	public static List<Integer> solve(int[] nums, int k) {
		Map<Integer, Integer> map = new HashMap<Integer, Integer>();
		List<Integer>[] list = new List[nums.length + 1];
		List<Integer> result = new ArrayList<>();

		for (int num : nums) {
			map.put(num, map.getOrDefault(num, 0) + 1);
		}

		for (int key : map.keySet()) {
			int topFreq = map.get(key);
			if (list[topFreq] == null) {
				list[topFreq] = new ArrayList<Integer>();
			}
			list[topFreq].add(key);

		}

		for (int lastIndex = list.length - 1; lastIndex >= 0; lastIndex--) {
			if (list[lastIndex] != null) {
				// System.out.println(list[lastIndex]);
				for (int i = 0; i < list[lastIndex].size() && result.size() < k; i++) {
					result.add(list[lastIndex].get(i));
				}
			}
		}

		return result;
	}

}