Added tasks 201-203.

src/main/java/g0201_0300/s0201_bitwise_and_of_numbers_range/Solution.java

@@ -0,0 +1,43 @@
+package g0201_0300.s0201_bitwise_and_of_numbers_range;
+
+public class Solution {
+    private static final int[] MASKS =
+            new int[] {
+                0,
+                0x80000000,
+                0xC0000000,
+                0xE0000000,
+                0xF0000000,
+                0xF8000000,
+                0xFC000000,
+                0xFE000000,
+                0xFF000000,
+                0xFF800000,
+                0xFFC00000,
+                0xFFE00000,
+                0xFFF00000,
+                0xFFF80000,
+                0xFFFC0000,
+                0xFFFE0000,
+                0xFFFF0000,
+                0xFFFF8000,
+                0xFFFFC000,
+                0xFFFFE000,
+                0xFFFFF000,
+                0xFFFFF800,
+                0xFFFFFC00,
+                0xFFFFFE00,
+                0xFFFFFF00,
+                0xFFFFFF80,
+                0xFFFFFFC0,
+                0xFFFFFFE0,
+                0xFFFFFFF0,
+                0xFFFFFFF8,
+                0xFFFFFFFC,
+                0xFFFFFFFE
+            };
+
+    public int rangeBitwiseAnd(int left, int right) {
+        return left == right ? left : right & MASKS[Integer.numberOfLeadingZeros(left ^ right)];
+    }
+}

src/main/java/g0201_0300/s0202_happy_number/Solution.java

@@ -0,0 +1,28 @@
+package g0201_0300.s0202_happy_number;
+
+public class Solution {
+    public boolean isHappy(int n) {
+        boolean happy = false;
+        int a = n;
+        int rem = 0;
+        int sum = 0;
+        if (a == 1 || a == 7) {
+            happy = true;
+        } else if (a > 1 && a < 10) {
+            happy = false;
+        } else {
+            while (a != 0) {
+                rem = a % 10;
+                sum = sum + (rem * rem);
+                a = a / 10;
+            }
+            if (sum != 1) {
+                happy = isHappy(sum);
+            } else {
+                happy = true;
+            }
+        }
+
+        return happy;
+    }
+}

src/main/java/g0201_0300/s0203_remove_linked_list_elements/Solution.java

@@ -0,0 +1,35 @@
+package g0201_0300.s0203_remove_linked_list_elements;
+
+import com_github_leetcode.ListNode;
+
+/*
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+public class Solution {
+    public ListNode removeElements(ListNode head, int val) {
+        if (head == null) {
+            return null;
+        }
+        while (head != null && head.val == val) {
+            head = head.next;
+        }
+        ListNode r = head;
+        ListNode t = head;
+        while (r != null) {
+            if (r.val == val) {
+                t.next = r.next;
+            } else {
+                t = r;
+            }
+            r = r.next;
+        }
+        return head;
+    }
+}

src/test/java/g0201_0300/s0201_bitwise_and_of_numbers_range/SolutionTest.java

@@ -0,0 +1,23 @@
+package g0201_0300.s0201_bitwise_and_of_numbers_range;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.Test;
+
+public class SolutionTest {
+    @Test
+    public void rangeBitwiseAnd() {
+        assertThat(new Solution().rangeBitwiseAnd(5, 7), equalTo(4));
+    }
+
+    @Test
+    public void rangeBitwiseAnd2() {
+        assertThat(new Solution().rangeBitwiseAnd(0, 0), equalTo(0));
+    }
+
+    @Test
+    public void rangeBitwiseAnd3() {
+        assertThat(new Solution().rangeBitwiseAnd(1, 2147483647), equalTo(0));
+    }
+}

src/test/java/g0201_0300/s0202_happy_number/SolutionTest.java

@@ -0,0 +1,13 @@
+package g0201_0300.s0202_happy_number;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import org.junit.Test;
+
+public class SolutionTest {
+    @Test
+    public void isHappy() {
+        assertThat(new Solution().isHappy(19), equalTo(true));
+    }
+}

src/test/java/g0201_0300/s0203_remove_linked_list_elements/SolutionTest.java

@@ -0,0 +1,22 @@
+package g0201_0300.s0203_remove_linked_list_elements;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+import com_github_leetcode.ListNode;
+import org.junit.Test;
+
+public class SolutionTest {
+    @Test
+    public void removeElements() {
+        ListNode headActual = new ListNode(1);
+        headActual.next = new ListNode(2);
+        headActual.next.next = new ListNode(6);
+        headActual.next.next.next = new ListNode(3);
+        headActual.next.next.next.next = new ListNode(4);
+        headActual.next.next.next.next.next = new ListNode(5);
+        headActual.next.next.next.next.next.next = new ListNode(6);
+        assertThat(
+                new Solution().removeElements(headActual, 6).toString(), equalTo("1, 2, 3, 4, 5"));
+    }
+}