"is it binary search tree hard" done!

not too bad, just allowing the right node being equal or greater. Two
modifications to the code was needed.

2 files changed, 29 insertions, 2 deletions

diff --git a/src/main/TreeBstCheck.java b/src/main/TreeBstCheck.java
index 51f33c4..4258306 100644
--- a/src/main/TreeBstCheck.java
+++ b/src/main/TreeBstCheck.java
@@ -56,14 +56,14 @@ public class TreeBstCheck {
                     } else {
                         int i = keyIndexStack.pop();
                         if (result.size() > 0) {
-                            if (key[i] <= result.get(result.size()-1)) return false;
+                            if (key[i] < result.get(result.size()-1)) return false;
                         }
                         result.add(key[i]);
                         walkLeft = false;
                     }
                 } else {
                     if (right[currentIndex] != -1) {
-                        if (key[right[currentIndex]] <= key[currentIndex]) return false;
+                        if (key[right[currentIndex]] < key[currentIndex]) return false;
                         currentIndex = right[currentIndex];
                         keyIndexStack.push(currentIndex);
                         walkLeft = true;
diff --git a/src/test/TreeBstCheckTest.java b/src/test/TreeBstCheckTest.java
index 7002d3e..35b66b4 100644
--- a/src/test/TreeBstCheckTest.java
+++ b/src/test/TreeBstCheckTest.java
@@ -57,4 +57,31 @@ class TreeBstCheckTest {
 
         assertFalse(tt.isBst());
     }
+    @Test
+    void test6() {
+        TreeBstCheck.TreeOrders tt = new TreeBstCheck.TreeOrders();
+        tt.key = new int[]{2, 1, 2};
+        tt.left = new int[]{1, -1, -1};
+        tt.right = new int[]{2, -1, -1};
+
+        assertTrue(tt.isBst());
+    }
+    @Test
+    void test7() {
+        TreeBstCheck.TreeOrders tt = new TreeBstCheck.TreeOrders();
+        tt.key = new int[]{2, 2, 3};
+        tt.left = new int[]{1, -1, -1};
+        tt.right = new int[]{2, -1, -1};
+
+        assertFalse(tt.isBst());
+    }
+    @Test
+    void test8() {
+        TreeBstCheck.TreeOrders tt = new TreeBstCheck.TreeOrders();
+        tt.key = new int[]{2147483647};
+        tt.left = new int[]{-1};
+        tt.right = new int[]{-1};
+
+        assertTrue(tt.isBst());
+    }
 }