add Java solution for 1146

Author: fishercoder1534

paginated_contents/algorithms/2nd_thousand/README.md

@@ -386,8 +386,8 @@
 | 1152 | [Analyze User Website Visit Pattern](https://leetcode.com/problems/analyze-user-website-visit-pattern/)                                                                                       | [Solution](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/secondthousand/_1152.java)                                          | [:tv:](https://youtu.be/V510Lbtrm5s)                | Medium                           | HashTable, Sort, Array                                               |
 | 1151 | [Minimum Swaps to Group All 1's Together](https://leetcode.com/problems/minimum-swaps-to-group-all-1s-together/)                                                                              | [Solution](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/secondthousand/_1151.java)                                          || Medium                                              | Array, Sliding Window            |
 | 1150 | [Check If a Number Is Majority Element in a Sorted Array](https://leetcode.com/problems/check-if-a-number-is-majority-element-in-a-sorted-array/)                                             | [Solution](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/secondthousand/_1150.java)                                          | [:tv:](https://youtu.be/-t2cdVs9cKk)                | Easy                             ||
-| 1146 | [Snapshot Array](https://leetcode.com/problems/snapshot-array/)                                                                                                                               | [Javascript](./javascript/_1146.js)                                                                                                                                            |                                                     | Easy                             ||
-| 1143 | [Longest Common Subsequence](https://leetcode.com/problems/longest-common-subsequence/)                                                                                                       | [Solution](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/secondthousand/_1143.java)                                          |                                                     | Medium                           ||String, DP
+| 1146 | [Snapshot Array](https://leetcode.com/problems/snapshot-array/)                                                                                                                               | [Javascript](./javascript/_1146.js) [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/secondthousand/_1146.java)          |                                                     | Easy                             ||
+| 1143 | [Longest Common Subsequence](https://leetcode.com/problems/longest-common-subsequence/)                                                                                                       | [Solution](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/secondthousand/_1143.java)                                          |                                                     | Medium                           |String, DP
 | 1138 | [Alphabet Board Path](https://leetcode.com/problems/alphabet-board-path/)                                                                                                                     | [Solution](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/secondthousand/_1138.java)                                          | [:tv:](https://youtu.be/rk-aB4rEOyU)                | Medium                           | HashTable, String                                                    |
 | 1137 | [N-th Tribonacci Number](https://leetcode.com/problems/n-th-tribonacci-number/)                                                                                                               | [Solution](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/secondthousand/_1137.java)                                          |                                                     | Easy                             ||
 | 1136 | [Parallel Courses](https://leetcode.com/problems/parallel-courses/)                                                                                                                           | [Solution](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/secondthousand/_1136.java)                                          |                                                     | Medium                           ||

src/main/java/com/fishercoder/solutions/secondthousand/_1146.java

@@ -0,0 +1,33 @@
+package com.fishercoder.solutions.secondthousand;
+
+import java.util.*;
+
+public class _1146 {
+    public static class Solution1 {
+        public static class SnapshotArray {
+            TreeMap<Integer, Integer>[] snapshots;//using this data structure is much more efficient in terms of storage, esp. if snap() calls happen frequently
+            int snapId;
+
+            public SnapshotArray(int length) {
+                snapshots = new TreeMap[length];
+                snapId = 0;
+                for (int i = 0; i < length; i++) {
+                    snapshots[i] = new TreeMap<>();
+                    snapshots[i].put(0, 0);
+                }
+            }
+
+            public void set(int index, int val) {
+                snapshots[index].put(snapId, val);
+            }
+
+            public int snap() {
+                return snapId++;
+            }
+
+            public int get(int index, int snap_id) {
+                return snapshots[index].floorEntry(snap_id).getValue();
+            }
+        }
+    }
+}

src/test/java/com/fishercoder/secondthousand/_1146Test.java

@@ -0,0 +1,37 @@
+package com.fishercoder.secondthousand;
+
+import com.fishercoder.solutions.secondthousand._1146;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _1146Test {
+    private static _1146.Solution1.SnapshotArray snapshotArray;
+
+    @BeforeEach
+    public void setup() {
+
+    }
+
+    @Test
+    public void test1() {
+        snapshotArray = new _1146.Solution1.SnapshotArray(3);
+        snapshotArray.set(0, 5);
+        snapshotArray.snap();
+        snapshotArray.set(0, 6);
+        assertEquals(5, snapshotArray.get(0, 0));
+    }
+
+    @Test
+    public void test2() {
+        snapshotArray = new _1146.Solution1.SnapshotArray(2);
+        snapshotArray.snap();
+        snapshotArray.set(1, 17);
+        snapshotArray.set(0, 20);
+        snapshotArray.snap();
+        snapshotArray.snap();
+        snapshotArray.snap();
+    }
+
+}