Code cleanup (#4246)

src/main/java/com/thealgorithms/misc/Sort012D.java

@@ -21,6 +21,7 @@ public class Sort012D {
             a[i] = np.nextInt();
         }
         sort012(a);
+        np.close();
     }
 
     public static void sort012(int[] a) {

src/main/java/com/thealgorithms/misc/Sparcity.java

@@ -49,5 +49,6 @@ class Sparcity {
             }
         }
         System.out.println("Sparcity of matrix is: " + sparcity(mat));
+        in.close();
     }
 }

src/main/java/com/thealgorithms/misc/ThreeSumProblem.java

@@ -19,6 +19,7 @@ public class ThreeSumProblem {
         System.out.println("Brute Force Approach\n" + (th.BruteForce(arr, ts)) + "\n");
         System.out.println("Two Pointer Approach\n" + (th.TwoPointer(arr, ts)) + "\n");
         System.out.println("Hashmap Approach\n" + (th.Hashmap(arr, ts)));
+        scan.close();
     }
 
     public List<List<Integer>> BruteForce(int[] nums, int target) {