add: finding-the-maximum-depth-of-a-binary-tree

Author: supercodestart

finding-the-maximum-depth-of-a-binary-tree/README.md

@@ -0,0 +1,35 @@
+# Finding the maximum depth of a binary tree
+
+The maximum depth of a binary tree is the number of nodes from the root down to the furthest leaf node. In other words, it is the height of a binary tree.
+
+## Input
+
+```console
+1, 2, 3, 4, -1, 5, 6, -1, -1, -1, -1, 7, 8, -1, 9, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 10, -1, -1, -1, 11, -1
+```
+
+Above array means below binary tree. An empty node is displayed as `-1`.
+
+```console
+    1
+   / \
+  2   3
+ /   / \
+4   5   6
+   / \   \
+  7   8   9
+     /   /
+    10  11
+```
+
+## Output
+
+```console
+4
+```
+
+## Execute
+
+```bash
+node solution.js
+```

finding-the-maximum-depth-of-a-binary-tree/solution.js

@@ -0,0 +1,46 @@
+const solution = (tree) => {
+  const makeNode = (
+    values,
+    offset = 0,
+    index = 0,
+    depth = 0,
+  ) => {
+    if (
+      !values ||
+      index >= values.length ||
+      values[index] === -1
+    ) {
+      return null;
+    }
+    const left = Math.pow(2, depth) + index + offset;
+    const right = Math.pow(2, depth) + index + 1 + offset;
+    return {
+      value: values[index],
+      left: makeNode(values, 0, left, depth + 1),
+      right: makeNode(values, 1, right, depth + 1),
+    };
+  };
+
+  const maxDepth = (node) => {
+    if (!node) {
+      return 0;
+    }
+    if (!node.left && !node.right) {
+      return 1;
+    }
+    const left = maxDepth(node.left);
+    const right = maxDepth(node.right);
+    return Math.max(left, right) + 1;
+  };
+
+  return maxDepth(makeNode(tree));
+};
+
+(() => {
+  const tree = [
+    1, 2, 3, 4, -1, 5, 6, -1, -1, -1, -1, 7, 8, -1, 9, -1,
+    -1, -1, -1, -1, -1, -1, -1, -1, -1, 10, -1, -1, -1, 11,
+    -1,
+  ];
+  console.log(solution(tree));
+})();