Reorganize folder structure

Files are now organized into folders named for their respective
approach.

Any files that were created for studying will not have a number prefix
as they did not originate from leetcode/CTCI.

.gitignore

@@ -1 +1 @@
-*.class
+.vscode/

Pascale_Triangle_118.java → Arrays/118_Pascale_Triangle.java

@@ -18,14 +18,4 @@ public static List<List<Integer>> generate(int numRows) {
 
         return result;
     }
-
-    public static void main(String[] args) {
-        int n = 5;
-        List<List<Integer>> result = generate(n);
-
-        for (List<Integer> l : result) {
-            System.out.println(l);
-        }
-        return;
-    }
 }

Pascale_Triangle_II_119.java → Arrays/119_Pascale_Triangle_II.java

@@ -15,14 +15,4 @@ public static List<Integer> getRow(int rowIndex) {
 
         return row;
     }
-
-    public static void main(String[] args) {
-        int n = 3;
-        List<Integer> result = getRow(n);
-
-        for (Integer l : result) {
-            System.out.print(l + ", ");
-        }
-        return;
-    }
 }

Arrays/169_Majority_Element.java

@@ -0,0 +1,19 @@
+import java.util.HashMap;
+import java.util.Map;
+
+public class Majority_Element_169 {
+    public static int majorityElement(int[] nums) {
+        Map<Integer, Integer> hm = new HashMap<>();
+        int n = nums.length;
+        int result = 0;
+
+        for (int i = 0; i < n; i++) {
+            hm.put(nums[i], hm.getOrDefault(nums[i], 0) + 1);
+            if (hm.get(nums[i]) > n / 2) {
+                result = nums[i];
+            }
+        }
+
+        return result;
+    }
+}

TwoSum.java → Arrays/1_TwoSum.java

@@ -1,6 +1,6 @@
 import java.util.HashMap;
 
-public class TwoSum {
+public class TwoSum_1 {
     public static int[] twoSum(int[] nums, int target) {
         HashMap<Integer, Integer> hm = new HashMap<>();
         int[] indices = new int[2];
@@ -10,25 +10,12 @@ public static int[] twoSum(int[] nums, int target) {
             if (hm.containsKey(remainder)) {
                 indices[0] = hm.get(remainder);
                 indices[1] = i;
-                break;
+                return indices;
             }
 
             hm.put(nums[i], i);
         }
 
-        return indices;
-    }
-
-    public static void main(String[] args) {
-        int[] nums = new int[] { -1, -2, 2, 6, 9, -10, -3 };
-        int target = 0;
-
-        int[] result = twoSum(nums, target);
-
-        System.out.println("The indicies of the two values that add up to " + target + " are: ");
-        for (Integer i : result) {
-            System.out.println(i);
-        }
-        return;
+        return new int[] {};
     }
 }

Product_Of_Array_Except_Itself_238.java → Arrays/238_Product_Of_Array_Except_Itself.java

@@ -14,28 +14,11 @@ public static int[] productExceptSelf(int[] nums) {
 
         productSoFar = 1;
 
-        int[] result2 = new int[nums.length];
         for (int i = nums.length - 1; i >= 0; i--) {
-            result2[i] = productSoFar;
+            result[i] *= productSoFar;
             productSoFar *= nums[i];
         }
 
         return result;
     }
-
-    public static void main(String[] args) {
-        // int[] nums = new int[] { 3, 1, 2, 5, 6, 4 };
-        int[] nums = new int[] { 1, 2, 3, 4 };
-
-        int[] result = productExceptSelf(nums);
-
-        for (int i = 0; i < result.length; i++) {
-            System.out.print(result[i]);
-            if (i != result.length - 1) {
-                System.out.print(", ");
-            }
-        }
-
-        return;
-    }
 }

Intersection_of_Two_Arrays_349.java → Arrays/349_Intersection_of_Two_Arrays.java

@@ -18,32 +18,10 @@ public static int[] intersection(int[] nums1, int[] nums2) {
 
         int[] result = new int[intersection.size()];
         int idx = 0;
-        for (int i : intersection) {
-            result[idx++] = i;
+        for (int commonVal : intersection) {
+            result[idx++] = commonVal;
         }
 
         return result;
     }
-
-    public static void main(String[] args) {
-        int[] arr1 = new int[] { 1, 2, 2, 1 };
-        int[] arr2 = new int[] { 2, 2 };
-
-        int[] result1 = intersection(arr1, arr2);
-        for (int i : result1) {
-            System.out.print(i + ", ");
-        }
-
-        System.out.println();
-
-        int[] arr3 = new int[] { 4, 9, 5 };
-        int[] arr4 = new int[] { 9, 4, 9, 8, 4 };
-
-        int[] result2 = intersection(arr3, arr4);
-        for (int i : result2) {
-            System.out.print(i + ", ");
-        }
-
-        return;
-    }
 }

Arrays/350_Intersection_of_Two_Arrays_II.java

@@ -0,0 +1,31 @@
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class Intersection_of_Two_Arrays_II_350 {
+    public static int[] intersect(int[] nums1, int[] nums2) {
+        Map<Integer, Integer> hm = new HashMap<>();
+        List<Integer> intersection = new ArrayList<>();
+
+        for (int i = 0; i < nums1.length; i++) {
+            hm.put(nums1[i], hm.getOrDefault(nums1[i], 0) + 1);
+        }
+
+        for (int i = 0; i < nums2.length; i++) {
+            int freq = hm.getOrDefault(nums2[i], 0);
+            if (freq > 0) {
+                intersection.add(nums2[i]);
+                hm.put(nums2[i], --freq);
+            }
+        }
+
+        int[] result = new int[intersection.size()];
+        int idx = 0;
+        for (int commonVal : intersection) {
+            result[idx++] = commonVal;
+        }
+
+        return result;
+    }
+}