[N-0] add 697

Author: fishercoder1534

README.md

@@ -22,6 +22,7 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Difficulty  | Tag          | Notes
 |-----|----------------|---------------|---------------|---------------|-------------|--------------|-----
+|697|[Degree of an Array](https://leetcode.com/problems/degree-of-an-array/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_697.java) | O(n) | O(n) | Easy | 
 |695|[Max Area of Island](https://leetcode.com/problems/max-area-of-island/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_695.java) | O(m*n) | O(1) | Easy | DFS
 |694|[Number of Distinct Islands](https://leetcode.com/problems/number-of-distinct-islands/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_694.java) | O(m*n) | O(1) | Medium | DFS
 |693|[Binary Number with Alternating Bits](https://leetcode.com/problems/binary-number-with-alternating-bits/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_693.java) | O(n) | O(1) | Easy | 

src/main/java/com/fishercoder/solutions/_697.java

@@ -0,0 +1,80 @@
+package com.fishercoder.solutions;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * 697. Degree of an Array
+ *
+ * Given a non-empty array of non-negative integers nums, the degree of this array is defined as the maximum frequency of any one of its elements.
+ * Your task is to find the smallest possible length of a (contiguous) subarray of nums, that has the same degree as nums.
+
+ Example 1:
+
+ Input: [1, 2, 2, 3, 1]
+ Output: 2
+ Explanation:
+ The input array has a degree of 2 because both elements 1 and 2 appear twice.
+ Of the subarrays that have the same degree:
+ [1, 2, 2, 3, 1], [1, 2, 2, 3], [2, 2, 3, 1], [1, 2, 2], [2, 2, 3], [2, 2]
+ The shortest length is 2. So return 2.
+
+ Example 2:
+ Input: [1,2,2,3,1,4,2]
+ Output: 6
+
+ Note:
+ nums.length will be between 1 and 50,000.
+ nums[i] will be an integer between 0 and 49,999.
+ */
+public class _697 {
+    public static class Solution1 {
+        public int findShortestSubArray(int[] nums) {
+            Map<Integer, Integer> map = new HashMap<>();
+            for (int i = 0; i < nums.length; i++) {
+                if (map.containsKey(nums[i])) {
+                    map.put(nums[i], map.get(nums[i]) + 1);
+                } else {
+                    map.put(nums[i], 1);
+                }
+            }
+            int degree = -1;
+            for (int key : map.keySet()) {
+                degree = Math.max(degree, map.get(key));
+            }
+            List<Integer> candidateNums = new ArrayList();
+            for (int key : map.keySet()) {
+                if (map.get(key) == degree) {
+                    candidateNums.add(key);
+                }
+            }
+            int shortest = Integer.MAX_VALUE;
+            for (int candidate : candidateNums) {
+                shortest = Math.min(shortest, findLength(nums, candidate));
+            }
+            return shortest;
+        }
+
+        int findLength(int[] arr, int candidate) {
+            {
+                int firstAppearance = Integer.MAX_VALUE;
+                for (int i = 0; i < arr.length; i++) {
+                    if (arr[i] == candidate) {
+                        firstAppearance = i;
+                        break;
+                    }
+                }
+                int lastAppearance = arr.length - 1;
+                for (int i = arr.length - 1; i > firstAppearance; i--) {
+                    if (arr[i] == candidate) {
+                        lastAppearance = i;
+                        break;
+                    }
+                }
+                return (lastAppearance - firstAppearance) + 1;
+            }
+        }
+    }
+}

src/test/java/com/fishercoder/_697Test.java

@@ -0,0 +1,24 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._697;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _697Test {
+    private static _697.Solution1 solution1;
+    private static int[] nums;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _697.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        nums = new int[]{1};
+        assertEquals(1, solution1.findShortestSubArray(nums));
+    }
+
+}