*

coding_interviews/algoexpert/find-closest-value-in-bst/find-closest-value-in-bst.js

@@ -0,0 +1,31 @@
+// Runtime: O(N), where N = number of nodes in the tree
+// Space: O(1)
+
+function findClosestValueInBst(tree, target, closestValue = null) {
+  if (!tree) {
+    return closestValue;
+  }
+
+  let currentDiff = Math.abs(tree.value - target);
+  let diff = closestValue ? Math.abs(closestValue - target) : currentDiff;
+  let leftValue = findClosestValueInBst(
+    tree.left,
+    target,
+    currentDiff <= diff ? tree.value : closestValue
+  );
+  let rightValue = findClosestValueInBst(
+    tree.right,
+    target,
+    currentDiff <= diff ? tree.value : closestValue
+  );
+  let leftDiff = Math.abs(leftValue - target);
+  let rightDiff = Math.abs(rightValue - target);
+
+  if (currentDiff <= leftDiff && currentDiff <= rightDiff) {
+    return tree.value;
+  } else if (leftDiff <= rightDiff) {
+    return leftValue;
+  }
+
+  return rightValue;
+}