Improved task 100.

Author: javadev

src/main/java/g0001_0100/s0100_same_tree/Solution.java

@@ -21,23 +21,12 @@
  * }
  */
 public class Solution {
-    private boolean trav(TreeNode n, TreeNode m) {
-        if (n != null && m != null) {
-            if (n.val != m.val) {
-                return false;
-            }
-            return (trav(n.left, m.left) && trav(n.right, m.right));
-        } else {
-            return n == null && m == null;
-        }
-    }
-
     public boolean isSameTree(TreeNode p, TreeNode q) {
-        if (p == null && q == null) {
-            return true;
-        } else if (p == null || q == null) {
-            return false;
+        if (p == null || q == null) {
+            return p == null && q == null;
         }
-        return trav(p, q);
+        boolean b1 = isSameTree(p.left, q.left);
+        boolean b2 = isSameTree(p.right, q.right);
+        return p.val == q.val && b1 && b2;
     }
 }

src/test/java/g0001_0100/s0100_same_tree/SolutionTest.java

@@ -29,4 +29,21 @@ void isSameTree3() {
         TreeNode q = TreeUtils.constructBinaryTree(Arrays.asList(1, 1, 2));
         assertThat(new Solution().isSameTree(p, q), equalTo(false));
     }
+
+    @Test
+    void isSameTree4() {
+        TreeNode p = TreeUtils.constructBinaryTree(Arrays.asList(1, 2, 1));
+        assertThat(new Solution().isSameTree(p, null), equalTo(false));
+    }
+
+    @Test
+    void isSameTree5() {
+        TreeNode q = TreeUtils.constructBinaryTree(Arrays.asList(1, 1, 2));
+        assertThat(new Solution().isSameTree(null, q), equalTo(false));
+    }
+
+    @Test
+    void isSameTree6() {
+        assertThat(new Solution().isSameTree(null, null), equalTo(true));
+    }
 }