Adding Check if a binary tree is subtree of another binary tree

src/_DataStructures_/Trees/BinaryTree/check-binary-tree-subtree-another-binary-tree/index.js

@@ -0,0 +1,37 @@
+// Check if a binary tree is subtree of another binary tree 
+// Root of the source tree and the tree to be matched are provided in the parameters.
+// Return true/false based on whether or not the given tree is the subtree of the source tree
+// Time complexity : O(m*n) m is the number of nodes of the original tree, 
+// n is the number of nodes in the tree to be matched
+
+function areIdentical(rootOfOriginalTree, rootOfMatchingTree) {
+    if (rootOfOriginalTree === null && rootOfMatchingTree === null) {
+        return true;
+    }
+
+    if (rootOfOriginalTree === null || rootOfMatchingTree === null) {
+        return false;
+    }
+
+    return (rootOfOriginalTree.value === rootOfMatchingTree.value) && areIdentical(rootOfOriginalTree.leftChild, rootOfMatchingTree.leftChild) && areIdentical(rootOfOriginalTree.rightChild, rootOfMatchingTree.rightChild);
+}
+
+function isSubtree(rootOfOriginalTree, rootOfMatchingTree) {
+    if (rootOfMatchingTree === null) {
+        return true;
+    }
+
+    if (rootOfOriginalTree === null) {
+        return false;
+    }
+
+    if (areIdentical(rootOfOriginalTree, rootOfMatchingTree)) {
+        return true;
+    }
+
+    return isSubtree(rootOfOriginalTree.leftChild, rootOfMatchingTree) || isSubtree(rootOfMatchingTree.rightChild, rootOfMatchingTree);
+}
+
+module.exports = {
+    isSubtree,
+};