add 1342

fishercoder1534 · fishercoder1534 · commit 1ad58ef286e4 · 2020-02-02T08:36:06.000-08:00
diff --git a/README.md b/README.md
@@ -9,6 +9,7 @@ _If you like this project, please leave me a star._ &#9733;
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
 |1343|[Maximum Product of Splitted Binary Tree](https://leetcode.com/problems/maximum-product-of-splitted-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1343.java) | |Medium||
+|1342|[Reduce Array Size to The Half](https://leetcode.com/problems/reduce-array-size-to-the-half/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1342.java) | |Medium||
 |1341|[The K Weakest Rows in a Matrix](https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1341.java) | |Easy||
 |1333|[Filter Restaurants by Vegan-Friendly, Price and Distance](https://leetcode.com/problems/filter-restaurants-by-vegan-friendly-price-and-distance/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1333.java) | |Medium||
 |1331|[Rank Transform of an Array](https://leetcode.com/problems/rank-transform-of-an-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1331.java) | |Easy||
diff --git a/src/main/java/com/fishercoder/solutions/_1342.java b/src/main/java/com/fishercoder/solutions/_1342.java
@@ -0,0 +1,60 @@
+package com.fishercoder.solutions;
+
+import java.util.*;
+
+/**
+ * 1342. Reduce Array Size to The Half
+ *
+ * Given an array arr.  You can choose a set of integers and remove all the occurrences of these integers in the array.
+ * Return the minimum size of the set so that at least half of the integers of the array are removed.
+ *
+ * Example 1:
+ * Input: arr = [3,3,3,3,5,5,5,2,2,7]
+ * Output: 2
+ * Explanation: Choosing {3,7} will make the new array [5,5,5,2,2] which has size 5 (i.e equal to half of the size of the old array).
+ * Possible sets of size 2 are {3,5},{3,2},{5,2}.
+ * Choosing set {2,7} is not possible as it will make the new array [3,3,3,3,5,5,5] which has size greater than half of the size of the old array.
+ *
+ * Example 2:
+ * Input: arr = [7,7,7,7,7,7]
+ * Output: 1
+ * Explanation: The only possible set you can choose is {7}. This will make the new array empty.
+ *
+ * Example 3:
+ * Input: arr = [1,9]
+ * Output: 1
+ *
+ * Example 4:
+ * Input: arr = [1000,1000,3,7]
+ * Output: 1
+ *
+ * Example 5:
+ * Input: arr = [1,2,3,4,5,6,7,8,9,10]
+ * Output: 5
+ *
+ * Constraints:
+ * 1 <= arr.length <= 10^5
+ * arr.length is even.
+ * 1 <= arr[i] <= 10^5
+ * */
+public class _1342 {
+    public static class Solution1 {
+        public int minSetSize(int[] arr) {
+            Map<Integer, Integer> map = new HashMap<>();
+            for (int i : arr) {
+                map.put(i, map.getOrDefault(i, 0) + 1);
+            }
+            List<Integer> list = new ArrayList<>();
+            for (int k : map.keySet()) {
+                list.add(map.get(k));
+            }
+            Collections.sort(list, Collections.reverseOrder());
+            int sum = 0;
+            int i = 0;
+            while (sum < arr.length / 2) {
+                sum += list.get(i++);
+            }
+            return i--;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_1342Test.java b/src/test/java/com/fishercoder/_1342Test.java
@@ -0,0 +1,48 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1342;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _1342Test {
+    private static _1342.Solution1 solution1;
+    private static int[] arr;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1342.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        arr = new int[]{3, 3, 3, 3, 5, 5, 5, 2, 2, 7};
+        assertEquals(2, solution1.minSetSize(arr));
+    }
+
+    @Test
+    public void test2() {
+        arr = new int[]{7, 7, 7, 7, 7, 7};
+        assertEquals(1, solution1.minSetSize(arr));
+    }
+
+    @Test
+    public void test3() {
+        arr = new int[]{1, 9};
+        assertEquals(1, solution1.minSetSize(arr));
+    }
+
+    @Test
+    public void test4() {
+        arr = new int[]{1000, 1000, 3, 7};
+        assertEquals(1, solution1.minSetSize(arr));
+    }
+
+    @Test
+    public void test5() {
+        arr = new int[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
+        assertEquals(5, solution1.minSetSize(arr));
+    }
+
+}
