solves majority element ii in java

Author: anishLearnsToCode

README.md

@@ -184,7 +184,7 @@
 | 225  | [Implement Stack using Queues](https://leetcode.com/problems/implement-stack-using-queues)                                                                |                                 [![Java](assets/java.png)](src/MyStack.java) [![Python](assets/python.png)](python/implement_stack_using_queues.py)                                  |                                                                                                                                   |
 | 226  | [Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree)                                                                                    |                                  [![Java](assets/java.png)](src/InvertBinaryTree.java) [![Python](assets/python.png)](python/invert_binary_tree.py)                                  |                                                                                                                                   |
 | 227  | [Basic Calculator II](https://leetcode.com/problems/basic-calculator-ii)                                                                                  |                                                                [![Java](assets/java.png)](src/BasicCalculatorII.java)                                                                |                                                                                                                                   |
-| 229  | [Majority Element II](https://leetcode.com/problems/majority-element-ii)                                                                                  |                                                                                                                                                                                      |                                                                                                                                   |
+| 229  | [Majority Element II](https://leetcode.com/problems/majority-element-ii)                                                                                  |                                                                [![Java](assets/java.png)](src/MajorityElementII.java)                                                                |                                                                                                                                   |
 | 230  | [Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst)                                                              |                                                                                                                                                                                      |                                                                                                                                   |
 | 231  | [Power of Two](https://leetcode.com/problems/power-of-two)                                                                                                |                                        [![Java](assets/java.png)](src/PowerOf2.java) [![Python](assets/python.png)](python/is_power_of_2.py)                                         |                                                                                                                                   |
 | 232  | [Implement Queue Using Stacks](https://leetcode.com/problems/implement-queue-using-stacks)                                                                |                                 [![Java](assets/java.png)](src/MyQueue.java) [![Python](assets/python.png)](python/implement_queue_using_stacks.py)                                  |                                                                                                                                   |

src/MajorityElementII.java

@@ -0,0 +1,42 @@
+// https://leetcode.com/problems/majority-element-ii
+// T: O(N)
+// S: O(1)
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class MajorityElementII {
+    public List<Integer> majorityElement(int[] nums) {
+        int candidate1 = 0, candidate2 = 0, frequency1 = 0, frequency2 = 0;
+        for (int element : nums) {
+            if (element == candidate1) frequency1++;
+            else if (element == candidate2) frequency2++;
+            else if (frequency1 == 0) {
+                candidate1 = element;
+                frequency1 = 1;
+            } else if (frequency2 == 0) {
+                candidate2 = element;
+                frequency2 = 1;
+            } else {
+                frequency1--;
+                frequency2--;
+            }
+        }
+        return confirmCandidates(nums, candidate1, candidate2);
+    }
+
+    private List<Integer> confirmCandidates(int[] array, int candidate1, int candidate2) {
+        final List<Integer> result = new ArrayList<>();
+        if (frequency(array, candidate1) > array.length / 3) result.add(candidate1);
+        if (candidate2 != candidate1 && frequency(array, candidate2) > array.length / 3) result.add(candidate2);
+        return result;
+    }
+
+    private int frequency(int[] array, int val) {
+        int count = 0;
+        for (int element : array) {
+            if (element == val) count++;
+        }
+        return count;
+    }
+}