diff --git a/README.md b/README.md
index 89473655c0..85f52b63e3 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,7 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|---------------|---------------|--------|-------------|-------------
+|1207|[Unique Number of Occurrences](https://leetcode.com/problems/unique-number-of-occurrences/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1207.java) | O(n) | O(1) | |Easy||
 |1160|[Find Words That Can Be Formed by Characters](https://leetcode.com/problems/find-words-that-can-be-formed-by-characters/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1160.java) | O(n) | O(m) | |Easy||
 |1154|[Day of the Year](https://leetcode.com/problems/day-of-the-year/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1154.java) | O(1) | O(1) | |Easy||
 |1137|[N-th Tribonacci Number](https://leetcode.com/problems/n-th-tribonacci-number/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1137.java) | O(n) | O(n) | |Easy||
diff --git a/src/main/java/com/fishercoder/common/utils/CommonUtils.java b/src/main/java/com/fishercoder/common/utils/CommonUtils.java
index e969aa8f96..87fd300b31 100644
--- a/src/main/java/com/fishercoder/common/utils/CommonUtils.java
+++ b/src/main/java/com/fishercoder/common/utils/CommonUtils.java
@@ -221,4 +221,14 @@ public static void printArrayArray(int[][] arrayArrays) {
         }
         System.out.println();
     }
+
+    public static void print2DCharArray(char[][] arrayArrays) {
+        for (char[] array : arrayArrays) {
+            for (char i : array) {
+                System.out.print(i + ", ");
+            }
+            System.out.println();
+        }
+        System.out.println();
+    }
 }
diff --git a/src/main/java/com/fishercoder/solutions/_1207.java b/src/main/java/com/fishercoder/solutions/_1207.java
new file mode 100644
index 0000000000..0d432c54fe
--- /dev/null
+++ b/src/main/java/com/fishercoder/solutions/_1207.java
@@ -0,0 +1,43 @@
+package com.fishercoder.solutions;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * 1207. Unique Number of Occurrences
+ *
+ * Given an array of integers arr,
+ * write a function that returns true if and only if the number of occurrences of each value in the array is unique.
+ *
+ * Example 1:
+ * Input: arr = [1,2,2,1,1,3]
+ * Output: true
+ * Explanation: The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.
+ *
+ * Example 2:
+ * Input: arr = [1,2]
+ * Output: false
+ *
+ * Example 3:
+ * Input: arr = [-3,0,1,-3,1,1,1,-3,10,0]
+ * Output: true
+ *
+ * Constraints:
+ * 1 <= arr.length <= 1000
+ * -1000 <= arr[i] <= 1000
+ * */
+public class _1207 {
+    public static class Solution1 {
+        public boolean uniqueOccurrences(int[] arr) {
+            Map<Integer, Integer> map = new HashMap<>();
+            Arrays.stream(arr).forEach(num -> {
+                map.put(num, map.containsKey(num) ? map.get(num) + 1 : 1);
+            });
+            Set<Integer> set = new HashSet<>();
+            return map.keySet().stream().mapToInt(key -> key).allMatch(key -> set.add(map.get(key)));
+        }
+    }
+}
diff --git a/src/main/java/com/fishercoder/solutions/_24.java b/src/main/java/com/fishercoder/solutions/_24.java
index 5d04c4e311..e7b07e484c 100644
--- a/src/main/java/com/fishercoder/solutions/_24.java
+++ b/src/main/java/com/fishercoder/solutions/_24.java
@@ -14,16 +14,17 @@
 
  */
 public class _24 {
-
-    public ListNode swapPairs(ListNode head) {
-        if (head == null || head.next == null) {
-            return head;
+    public static class Solution1 {
+        public ListNode swapPairs(ListNode head) {
+            if (head == null || head.next == null) {
+                return head;
+            }
+            ListNode second = head.next;
+            ListNode third = second.next;
+            second.next = head;
+            head.next = swapPairs(third);
+            return second;
         }
-        ListNode second = head.next;
-        ListNode third = second.next;
-        second.next = head;
-        head.next = swapPairs(third);
-        return second;
     }
 
 }
diff --git a/src/main/java/com/fishercoder/solutions/_35.java b/src/main/java/com/fishercoder/solutions/_35.java
index 318db230dc..ea88dc9669 100644
--- a/src/main/java/com/fishercoder/solutions/_35.java
+++ b/src/main/java/com/fishercoder/solutions/_35.java
@@ -18,14 +18,16 @@
 
 public class _35 {
 
-    public int searchInsert(int[] nums, int target) {
-        int len = nums.length;
-        for (int i = 0; i < len; i++) {
-            if (target <= nums[i]) {
-                return i;
+    public static class Solution1 {
+        public int searchInsert(int[] nums, int target) {
+            int len = nums.length;
+            for (int i = 0; i < len; i++) {
+                if (target <= nums[i]) {
+                    return i;
+                }
             }
+            return len;
         }
-        return len;
     }
 
 }
diff --git a/src/main/java/com/fishercoder/solutions/_37.java b/src/main/java/com/fishercoder/solutions/_37.java
index 92d4c15282..3f7fcbf8c5 100644
--- a/src/main/java/com/fishercoder/solutions/_37.java
+++ b/src/main/java/com/fishercoder/solutions/_37.java
@@ -3,9 +3,53 @@
 /**
  * 37. Sudoku Solver
  *
- * Write a program to solve a Sudoku puzzle by filling the empty cells.
- * Empty cells are indicated by the character '.'.
- * You may assume that there will be only one unique solution.
+ * Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:
+ *
+ * Each row must contain the digits 1-9 without repetition.
+ * Each column must contain the digits 1-9 without repetition.
+ * Each of the 9 3x3 sub-boxes of the grid must contain the digits 1-9 without repetition.
+ *
+ * The Sudoku board could be partially filled, where empty cells are filled with the character '.'.
+ *
+ * Example 1:
+ *
+ * Input:
+ * [
+ *   ["5","3",".",".","7",".",".",".","."],
+ *   ["6",".",".","1","9","5",".",".","."],
+ *   [".","9","8",".",".",".",".","6","."],
+ *   ["8",".",".",".","6",".",".",".","3"],
+ *   ["4",".",".","8",".","3",".",".","1"],
+ *   ["7",".",".",".","2",".",".",".","6"],
+ *   [".","6",".",".",".",".","2","8","."],
+ *   [".",".",".","4","1","9",".",".","5"],
+ *   [".",".",".",".","8",".",".","7","9"]
+ * ]
+ * Output: true
+ * Example 2:
+ *
+ * Input:
+ * [
+ *   ["8","3",".",".","7",".",".",".","."],
+ *   ["6",".",".","1","9","5",".",".","."],
+ *   [".","9","8",".",".",".",".","6","."],
+ *   ["8",".",".",".","6",".",".",".","3"],
+ *   ["4",".",".","8",".","3",".",".","1"],
+ *   ["7",".",".",".","2",".",".",".","6"],
+ *   [".","6",".",".",".",".","2","8","."],
+ *   [".",".",".","4","1","9",".",".","5"],
+ *   [".",".",".",".","8",".",".","7","9"]
+ * ]
+ * Output: false
+ * Explanation: Same as Example 1, except with the 5 in the top left corner being
+ *     modified to 8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.
+ * Note:
+ *
+ * A Sudoku board (partially filled) could be valid but is not necessarily solvable.
+ * Only the filled cells need to be validated according to the mentioned rules.
+ * The given board contain only digits 1-9 and the character '.'.
+ * The given board size is always 9x9.
+ *
  */
 public class _37 {
 
diff --git a/src/test/java/com/fishercoder/_1207Test.java b/src/test/java/com/fishercoder/_1207Test.java
new file mode 100644
index 0000000000..8b3e326fac
--- /dev/null
+++ b/src/test/java/com/fishercoder/_1207Test.java
@@ -0,0 +1,35 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1207;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _1207Test {
+    private static _1207.Solution1 solution1;
+    private static int[] arr;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1207.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        arr = new int[]{1, 2, 2, 1, 1, 3};
+        assertEquals(true, solution1.uniqueOccurrences(arr));
+    }
+
+    @Test
+    public void test2() {
+        arr = new int[]{1, 2};
+        assertEquals(false, solution1.uniqueOccurrences(arr));
+    }
+
+    @Test
+    public void test3() {
+        arr = new int[]{-3, 0, 1, -3, 1, 1, 1, -3, 10, 0};
+        assertEquals(true, solution1.uniqueOccurrences(arr));
+    }
+}
diff --git a/src/test/java/com/fishercoder/_24Test.java b/src/test/java/com/fishercoder/_24Test.java
new file mode 100644
index 0000000000..98a53a8aa5
--- /dev/null
+++ b/src/test/java/com/fishercoder/_24Test.java
@@ -0,0 +1,26 @@
+package com.fishercoder;
+
+import com.fishercoder.common.classes.ListNode;
+import com.fishercoder.common.utils.CommonUtils;
+import com.fishercoder.solutions._24;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.util.Arrays;
+
+public class _24Test {
+    private static _24.Solution1 solution1;
+    private static ListNode head;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _24.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        head = ListNode.createSinglyLinkedList(Arrays.asList(1, 2, 3, 4));
+        CommonUtils.printList(solution1.swapPairs(head));
+    }
+
+}
\ No newline at end of file
diff --git a/src/test/java/com/fishercoder/_29Test.java b/src/test/java/com/fishercoder/_29Test.java
new file mode 100644
index 0000000000..9f9ebc10c7
--- /dev/null
+++ b/src/test/java/com/fishercoder/_29Test.java
@@ -0,0 +1,21 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._29;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _29Test {
+    private static _29.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _29.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(1, solution1.divide(4, 3));
+    }
+}
diff --git a/src/test/java/com/fishercoder/_31Test.java b/src/test/java/com/fishercoder/_31Test.java
new file mode 100644
index 0000000000..98ee63a8e1
--- /dev/null
+++ b/src/test/java/com/fishercoder/_31Test.java
@@ -0,0 +1,23 @@
+package com.fishercoder;
+
+import com.fishercoder.common.utils.CommonUtils;
+import com.fishercoder.solutions._31;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class _31Test {
+    private static _31.Solution1 solution1;
+    private static int[] nums;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _31.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        nums = new int[]{1, 2, 3};
+        solution1.nextPermutation(nums);
+        CommonUtils.printArray(nums);
+    }
+}
diff --git a/src/test/java/com/fishercoder/_32Test.java b/src/test/java/com/fishercoder/_32Test.java
new file mode 100644
index 0000000000..c1db3cfae9
--- /dev/null
+++ b/src/test/java/com/fishercoder/_32Test.java
@@ -0,0 +1,21 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._32;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _32Test {
+    private static _32.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _32.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(2, solution1.longestValidParentheses("(()"));
+    }
+}
diff --git a/src/test/java/com/fishercoder/_33Test.java b/src/test/java/com/fishercoder/_33Test.java
new file mode 100644
index 0000000000..aa0e6f14cd
--- /dev/null
+++ b/src/test/java/com/fishercoder/_33Test.java
@@ -0,0 +1,26 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._33;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _33Test {
+    private static _33.Solution1 solution1;
+    private static _33.Solution2 solution2;
+    private static int[] nums;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _33.Solution1();
+        solution2 = new _33.Solution2();
+    }
+
+    @Test
+    public void test1() {
+        nums = new int[]{4, 5, 6, 7, 0, 1, 2};
+        assertEquals(3, solution1.search(nums, 7));
+        assertEquals(3, solution2.search(nums, 7));
+    }
+}
diff --git a/src/test/java/com/fishercoder/_35Test.java b/src/test/java/com/fishercoder/_35Test.java
new file mode 100644
index 0000000000..3062dcd46a
--- /dev/null
+++ b/src/test/java/com/fishercoder/_35Test.java
@@ -0,0 +1,23 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._35;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _35Test {
+    private static _35.Solution1 solution1;
+    private static int[] nums;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _35.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        nums = new int[]{1, 3, 5, 6};
+        assertEquals(2, solution1.searchInsert(nums, 5));
+    }
+}
diff --git a/src/test/java/com/fishercoder/_37Test.java b/src/test/java/com/fishercoder/_37Test.java
new file mode 100644
index 0000000000..c058a24a6b
--- /dev/null
+++ b/src/test/java/com/fishercoder/_37Test.java
@@ -0,0 +1,34 @@
+package com.fishercoder;
+
+import com.fishercoder.common.utils.CommonUtils;
+import com.fishercoder.solutions._37;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class _37Test {
+    private static _37.Solution1 solution1;
+    private static char[][] board;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _37.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        board = new char[][]{
+                {'5', '3', '.', '.', '7', '.', '.', '.', '.'},
+                {'6', '.', '.', '1', '9', '5', '.', '.', '.'},
+                {'.', '9', '8', '.', '.', '.', '.', '6', '.'},
+                {'8', '3', '.', '.', '6', '.', '.', '.', '3'},
+                {'4', '.', '.', '8', '.', '3', '.', '.', '1'},
+                {'7', '.', '.', '.', '2', '.', '.', '.', '6'},
+                {'.', '6', '.', '.', '7', '.', '2', '8', '.'},
+                {'.', '.', '.', '4', '1', '9', '.', '.', '5'},
+                {'.', '.', '.', '.', '8', '.', '.', '7', '9'}
+        };
+        CommonUtils.print2DCharArray(board);
+        solution1.solveSudoku(board);
+        CommonUtils.print2DCharArray(board);
+    }
+}
diff --git a/src/test/java/com/fishercoder/_38Test.java b/src/test/java/com/fishercoder/_38Test.java
new file mode 100644
index 0000000000..d2d2644546
--- /dev/null
+++ b/src/test/java/com/fishercoder/_38Test.java
@@ -0,0 +1,21 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._38;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _38Test {
+    private static _38.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _38.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals("21", solution1.countAndSay(3));
+    }
+}
diff --git a/src/test/java/com/fishercoder/_46Test.java b/src/test/java/com/fishercoder/_46Test.java
new file mode 100644
index 0000000000..506567ecc5
--- /dev/null
+++ b/src/test/java/com/fishercoder/_46Test.java
@@ -0,0 +1,20 @@
+package com.fishercoder;
+
+import com.fishercoder.common.utils.CommonUtils;
+import com.fishercoder.solutions._46;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class _46Test {
+    private static _46.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _46.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        CommonUtils.printListList(solution1.permute(new int[]{1, 2, 3}));
+    }
+}
diff --git a/src/test/java/com/fishercoder/_58Test.java b/src/test/java/com/fishercoder/_58Test.java
new file mode 100644
index 0000000000..9dca450c7a
--- /dev/null
+++ b/src/test/java/com/fishercoder/_58Test.java
@@ -0,0 +1,21 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._58;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _58Test {
+    private static _58.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _58.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(5, solution1.lengthOfLastWord("Hello World"));
+    }
+}
diff --git a/src/test/java/com/fishercoder/_59Test.java b/src/test/java/com/fishercoder/_59Test.java
new file mode 100644
index 0000000000..dc31098345
--- /dev/null
+++ b/src/test/java/com/fishercoder/_59Test.java
@@ -0,0 +1,22 @@
+package com.fishercoder;
+
+import com.fishercoder.common.utils.CommonUtils;
+import com.fishercoder.solutions._59;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class _59Test {
+    private static _59.Solution1 solution1;
+    private static int[][] matrix;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _59.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        matrix = solution1.generateMatrix(6);
+        CommonUtils.print2DIntArray(matrix);
+    }
+}
diff --git a/src/test/java/com/fishercoder/_60Test.java b/src/test/java/com/fishercoder/_60Test.java
new file mode 100644
index 0000000000..0c28e11bb6
--- /dev/null
+++ b/src/test/java/com/fishercoder/_60Test.java
@@ -0,0 +1,21 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._60;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _60Test {
+    private static _60.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _60.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals("231", solution1.getPermutation(3, 4));
+    }
+}