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Fixed remove bug where node has 2 children. #8

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Fixed remove bug where node has 2 children. #8

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35 changes: 27 additions & 8 deletions data-structures/binary-search-tree/binary-search-tree-tests.htm
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Original file line number Diff line number Diff line change
Expand Up @@ -107,7 +107,7 @@ <h1>Binary Search Tree Tests</h1>

setUp: function(){
this.tree = new BinarySearchTree();
this.tree.add(5);
this.tree.add(4);
this.tree.add(10);
this.tree.add(6);
},
Expand All @@ -121,18 +121,18 @@ <h1>Binary Search Tree Tests</h1>
//---------------------------------------------------------------------

testRemoveFirstItem: function(){
this.tree.remove(5);
this.tree.remove(4);
assert.areEqual(2, this.tree.size(), "There should only be two items left.");
assert.areEqual(10, this.tree._root.value, "Root value should now be 10.");
assert.isFalse(this.tree.contains(5));
assert.isFalse(this.tree.contains(4));
},

testRemoveFirstItemToo: function(){
this.tree.remove(10);
this.tree.remove(5);
this.tree.remove(4);
assert.areEqual(1, this.tree.size(), "There should only be one item left.");
assert.areEqual(6, this.tree._root.value, "Root value should now be 6.");
assert.isFalse(this.tree.contains(5));
assert.isFalse(this.tree.contains(4));
assert.isFalse(this.tree.contains(10));
},

Expand All @@ -148,15 +148,34 @@ <h1>Binary Search Tree Tests</h1>
assert.isFalse(this.tree.contains(6));
},

testRemoveAnItemWithTwoChildren: function(){
this.tree.add(20); // Add another child to 10.
this.tree.add(5);
this.tree.add(7);
this.tree.remove(10);

assert.areEqual(5, this.tree.size(), "There should only be 5 items left.");
assert.isFalse(this.tree.contains(10));
},

testRemoveAnItemWithTwoChildrenWhereLeftSubTreeHasNoRightNodes: function(){
this.tree.add(20); // Add another child to 10.
this.tree.remove(10);

assert.areEqual(3, this.tree.size(), "There should only be 3 items left.");
assert.isFalse(this.tree.contains(10));
},

testRemoveLastAll: function(){
this.tree.remove(6);
this.tree.remove(5);
this.tree.remove(4);
this.tree.remove(10);
assert.areEqual(0, this.tree.size(), "There should only be two items left.");
assert.isFalse(this.tree.contains(6));
assert.isFalse(this.tree.contains(5));
assert.isFalse(this.tree.contains(4));
assert.isFalse(this.tree.contains(10));
}
}

}));

//-------------------------------------------------------------------------
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10 changes: 9 additions & 1 deletion data-structures/binary-search-tree/binary-search-tree.js
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Expand Up @@ -265,14 +265,22 @@ BinarySearchTree.prototype = {
//reset pointers for new traversal
replacement = current.left;
replacementParent = current;


//find the right-most node
while(replacement.right !== null){
replacementParent = replacement;
replacement = replacement.right;
}

replacementParent.right = replacement.left;

if (replacementParent.right === replacement) {
replacementParent.right = replacement.left;
} else {
//replacement will be on the left when the left most subtree
//of the node to remove has no children to the right
replacementParent.left = replacement.left;
}

//assign children to the replacement
replacement.right = current.right;
Expand Down