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BAEL-4864: Fix traverseInOrderWithoutRecursion method (#10588) 

Co-authored-by: Krzysztof Woyke <krzysztof.woyke.sp@lhsystems.com>
This commit is contained in:
kwoyke 2021-03-24 22:09:02 +01:00 committed by GitHub
parent 9a580ea9fc
commit 23503a0673
2 changed files with 53 additions and 30 deletions
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56
data-structures/src/main/java/com/baeldung/tree/BinaryTree.java
View File

@ -148,48 +148,46 @@ public class BinaryTree {
} }
} }
public void traverseInOrderWithoutRecursion() { public void traverseInOrderWithoutRecursion() {
Stack<Node> stack = new Stack<Node>(); Stack<Node> stack = new Stack<>();
Node current = root;
while (current != null || !stack.isEmpty()) {
while (current != null) {
stack.push(current);
current = current.left;
}
Node top = stack.pop();
visit(top.value);
current = top.right;
}
}
public void traversePreOrderWithoutRecursion() {
Stack<Node> stack = new Stack<>();
Node current = root; Node current = root;
stack.push(root); stack.push(root);
while(! stack.isEmpty()) {
while(current.left != null) { while (current != null && !stack.isEmpty()) {
current = current.left;
stack.push(current);
}
current = stack.pop(); current = stack.pop();
visit(current.value); visit(current.value);
if(current.right != null) {
current = current.right; if (current.right != null)
stack.push(current); stack.push(current.right);
}
if (current.left != null)
stack.push(current.left);
} }
} }
public void traversePreOrderWithoutRecursion() {
Stack<Node> stack = new Stack<Node>();
Node current = root;
stack.push(root);
while(! stack.isEmpty()) {
current = stack.pop();
visit(current.value);
if(current.right != null)
stack.push(current.right);
if(current.left != null)
stack.push(current.left);
}
}
public void traversePostOrderWithoutRecursion() { public void traversePostOrderWithoutRecursion() {
Stack<Node> stack = new Stack<Node>(); Stack<Node> stack = new Stack<>();
Node prev = root; Node prev = root;
Node current = root; Node current = root;
stack.push(root); stack.push(root);
while (!stack.isEmpty()) { while (current != null && !stack.isEmpty()) {
current = stack.peek(); current = stack.peek();
boolean hasChild = (current.left != null || current.right != null); boolean hasChild = (current.left != null || current.right != null);
boolean isPrevLastChild = (prev == current.right || (prev == current.left && current.right == null)); boolean isPrevLastChild = (prev == current.right || (prev == current.left && current.right == null));

27
data-structures/src/test/java/com/baeldung/tree/BinaryTreeUnitTest.java
View File

@ -13,7 +13,7 @@ public class BinaryTreeUnitTest {
BinaryTree bt = createBinaryTree(); BinaryTree bt = createBinaryTree();
assertTrue(!bt.isEmpty()); assertFalse(bt.isEmpty());
} }
@Test @Test
@ -72,6 +72,7 @@ public class BinaryTreeUnitTest {
@Test @Test
public void it_deletes_the_root() { public void it_deletes_the_root() {
int value = 12; int value = 12;
BinaryTree bt = new BinaryTree(); BinaryTree bt = new BinaryTree();
bt.add(value); bt.add(value);
@ -91,6 +92,14 @@ public class BinaryTreeUnitTest {
bt.traverseInOrderWithoutRecursion(); bt.traverseInOrderWithoutRecursion();
} }
@Test
public void givenAnEmptyBinaryTree_WhenTraversingInOrderWithoutRecursion_ThenNoException() {
BinaryTree empty = new BinaryTree();
empty.traverseInOrderWithoutRecursion();
}
@Test @Test
public void givenABinaryTree_WhenTraversingPreOrder_ThenPrintValues() { public void givenABinaryTree_WhenTraversingPreOrder_ThenPrintValues() {
@ -101,6 +110,14 @@ public class BinaryTreeUnitTest {
bt.traversePreOrderWithoutRecursion(); bt.traversePreOrderWithoutRecursion();
} }
@Test
public void givenAnEmptyBinaryTree_WhenTraversingPreOrderWithoutRecursion_ThenNoException() {
BinaryTree empty = new BinaryTree();
empty.traversePreOrderWithoutRecursion();
}
@Test @Test
public void givenABinaryTree_WhenTraversingPostOrder_ThenPrintValues() { public void givenABinaryTree_WhenTraversingPostOrder_ThenPrintValues() {
@ -111,6 +128,14 @@ public class BinaryTreeUnitTest {
bt.traversePostOrderWithoutRecursion(); bt.traversePostOrderWithoutRecursion();
} }
@Test
public void givenAnEmptyBinaryTree_WhenTraversingPostOrderWithoutRecursion_ThenNoException() {
BinaryTree empty = new BinaryTree();
empty.traversePostOrderWithoutRecursion();
}
@Test @Test
public void givenABinaryTree_WhenTraversingLevelOrder_ThenPrintValues() { public void givenABinaryTree_WhenTraversingLevelOrder_ThenPrintValues() {