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Update validateBST.js #25

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36 changes: 21 additions & 15 deletions chapter04/4.05 - Validate BST/validateBST.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,23 +4,29 @@ var BinaryTree = function(value) {
this.right = null;
};

var validateBST = function(bt) {
// traverse the tree depth first, while
// using a array with stack like behavior to check each node's validity
// * assume values do not repeat
var validateRecurse = function(currBt, stackArr) {
for (var i = 0; i < stackArr.length; i++) {
if (stackArr[i].side === 'left' && currBt.value > stackArr[i].node.value) {
return false;
} else if (stackArr[i].side === 'right' && currBt.value < stackArr[i].node.value) {
return false;
}
var validateBST = function(tree) {

var validateRecurse = function(tree, min, max) {
if (tree === null) {
return true;
}

if (tree.value <= min || tree.value >= max) {
return false;
}

if (!validateRecurse(tree.left, min, tree.value)) {
return false;
}

if (!validateRecurse(tree.right, tree.value, max)) {
return false;
}
var left = currBt.left === null ? true : validateRecurse(currBt.left, stackArr.concat([{ node:currBt, side:'left'}]));
var right = currBt.right === null ? true : validateRecurse(currBt.right, stackArr.concat([{ node:currBt, side:'right'}]));
return true && left && right;

return true;
};
return validateRecurse(bt, []);

return validateRecurse(tree, -Infinity, Infinity);
};

/* TESTS */
Expand Down