feat(leetcode): add No.384 java version

Author: mickey0524

384.Shuffle-an-Array.java

@@ -0,0 +1,51 @@
+// https://leetcode.com/problems/shuffle-an-array/
+//
+// algorithms
+// Medium (49.88%)
+// Total Accepted:    74,127
+// Total Submissions: 148,648
+
+
+class Solution {
+
+    private int[] nums;
+        
+    public Solution(int[] nums) {
+        this.nums = nums;
+    }
+    
+    /** Resets the array to its original configuration and return it. */
+    public int[] reset() {
+        return nums;
+    }
+    
+    /** Returns a random shuffling of the array. */
+    public int[] shuffle() {
+        int[] curNums = this.nums.clone();
+        int length = curNums.length;
+        int tail = length;
+        
+        Random random = new Random();
+        
+        for (int i = 0; i < length - 1; i++) {
+            int idx = random.nextInt(tail);
+            swap(curNums, idx, tail - 1);
+            tail--;
+        }
+        
+        return curNums;
+    }
+    
+    public void swap(int[] nums, int i, int j) {
+        int tmp = nums[i];
+        nums[i] = nums[j];
+        nums[j] = tmp;
+    }
+}
+
+/**
+ * Your Solution object will be instantiated and called as such:
+ * Solution obj = new Solution(nums);
+ * int[] param_1 = obj.reset();
+ * int[] param_2 = obj.shuffle();
+ */