Added p914 (#56)

Author: west-dBest

README.md

@@ -64,6 +64,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |925|[Long Pressed Name](https://leetcode.com/problems/long-pressed-name/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_925.java) | O(n) | O(1) | |Easy|
 |922|[Sort Array By Parity II](https://leetcode.com/problems/sort-array-by-parity-ii/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_922.java) | O(n) | O(1) | |Easy|
 |917|[Reverse Only Letters](https://leetcode.com/problems/reverse-only-letters/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_917.java) | O(n) | O(n) | |Easy|
+|914|[X of a Kind in a Deck of Cards](https://leetcode.com/problems/x-of-a-kind-in-a-deck-of-cards/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_914.java) | O(n) | O(n) | |Easy|
 |908|[Smallest Range I](https://leetcode.com/problems/smallest-range-i/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_908.java) | O(n) | O(1) | |Easy|
 |900|[RLE Iterator](https://leetcode.com/problems/rle-iterator/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_900.java) | O(n) | O(1) | |Medium|
 |897|[Increasing Order Search Tree](https://leetcode.com/problems/increasing-order-search-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_897.java) | O(n) | O(n) | |Easy| DFS, recursion

src/main/java/com/fishercoder/solutions/_914.java

@@ -0,0 +1,79 @@
+package com.fishercoder.solutions;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * In a deck of cards, each card has an integer written on it.
+ * Return true if and only if you can choose X >= 2 such that it is possible to split the entire deck into 1 or more groups of cards, where:
+ *  Each group has exactly X cards.
+ *  All the cards in each group have the same integer.
+ *
+ * Example 1:
+ * Input: [1,2,3,4,4,3,2,1]
+ * Output: true
+ * Explanation: Possible partition [1,1],[2,2],[3,3],[4,4]
+ *
+ * Example 2:
+ * Input: [1,1,1,2,2,2,3,3]
+ * Output: false
+ * Explanation: No possible partition.
+ *
+ * Example 3:
+ * Input: [1]
+ * Output: false
+ * Explanation: No possible partition.
+ *
+ * Example 4:
+ * Input: [1,1]
+ * Output: true
+ * Explanation: Possible partition [1,1]
+ *
+ * Example 5:
+ * Input: [1,1,2,2,2,2]
+ * Output: true
+ * Explanation: Possible partition [1,1],[2,2],[2,2]
+ */
+public class _914 {
+    public static class Solution1 {
+        public boolean hasGroupsSizeX(int[] deck) {
+            //Size too small for partitions
+            if (deck.length < 2)
+                return false;
+
+            //Track repetitions of values in deck array
+            Map<Integer, Integer> mapReps = new HashMap<>();
+            for (int card : deck) {
+                if (!mapReps.containsKey(card))
+                    mapReps.put(card,1);
+                else
+                    mapReps.put(card,mapReps.get(card)+1);
+            }
+
+            //Create array of map values
+            int num = 0;
+            int[] arrReps = new int[mapReps.size()];
+            for (Map.Entry<Integer,Integer> e : mapReps.entrySet()){
+                arrReps[num++] = e.getValue();
+            }
+
+            //Find greatest common denominator
+            num = arrGCD(arrReps, arrReps.length);
+
+            //If gcd of all repetitions is greater than 1, it's partitionable.
+            return num > 1;
+        }
+
+        private int gcd(int a, int b){
+            return b == 0 ? a : gcd(b, a % b);
+        }
+
+        private int arrGCD(int[] arr, int n){
+            int result = arr[0];
+            for (int i = 1; i < n; i++)
+                result = gcd(arr[i], result);
+
+            return result;
+        }
+    }
+}

src/test/java/com/fishercoder/_914Test.java

@@ -0,0 +1,53 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._914;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _914Test {
+    private static _914.Solution1 solution1;
+    private int[] arr;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _914.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        arr = new int[]{1};
+        assertEquals(false, solution1.hasGroupsSizeX(arr));
+    }
+
+    @Test
+    public void test2() {
+        arr = new int[]{1,1};
+        assertEquals(true, solution1.hasGroupsSizeX(arr));
+    }
+
+    @Test
+    public void test3() {
+        arr = new int[]{1,1,1,1,2,2,2,2,2,2};
+        assertEquals(true, solution1.hasGroupsSizeX(arr));
+    }
+
+    @Test
+    public void test4() {
+        arr = new int[]{1,1,1,2,2,2,3,3};
+        assertEquals(false, solution1.hasGroupsSizeX(arr));
+    }
+
+    @Test
+    public void test5() {
+        arr = new int[]{0,0,1,1,1,1,2,2,3,4};
+        assertEquals(false, solution1.hasGroupsSizeX(arr));
+    }
+
+    @Test
+    public void test6() {
+        arr = new int[]{1,2,3,4,4,3,2,1};
+        assertEquals(true, solution1.hasGroupsSizeX(arr));
+    }
+}