Question: https://leetcode.com/explore/challenge/card/march-leetcodin…

…g-challenge-2021/588/week-1-march-1st-march-7th/3661/

Average-Levels-BST/bst.cpp

@@ -0,0 +1,34 @@
+#include <iostream>
+
+using namespace std;
+
+struct TreeNode {
+  int val;
+  TreeNode *left, *right;
+};
+
+TreeNode *newNode(int val) {
+  TreeNode *node = (TreeNode*)malloc(sizeof(TreeNode));
+  node -> val = val;
+  node -> left = node -> right = NULL;
+  return node;
+}
+
+TreeNode *insertLevelOrder(int arr[], TreeNode *root, int i, int n) {
+  if (i < n) {
+    TreeNode *temp = newNode(arr[i]);
+    root = temp;
+
+    root -> left = insertLevelOrder(arr, root -> left, i * 2 + 1, n);
+    root -> right = insertLevelOrder(arr, root -> right, 2 * i + 2, n);
+  }
+  return root;
+}
+
+void inOrder(TreeNode *root) {
+  if (root != NULL) {
+    inOrder(root -> left);
+    cout << root -> val << " ";
+    inOrder(root -> right);
+  }
+}

Average-Levels-BST/main.cpp

@@ -0,0 +1,52 @@
+#include <iostream>
+#include <vector>
+#include <queue>
+#include <math.h>
+#include "bst.cpp"
+
+using namespace std;
+
+/**
+ * @see https://leetcode.com/explore/challenge/card/march-leetcoding-challenge-2021/588/week-1-march-1st-march-7th/3661/
+ */
+class Solution {
+public:
+  vector<double> averageOfLevels(TreeNode* root) {
+    vector<double> ans;
+    if (!root) return ans;
+    queue<TreeNode*> q;
+    q.push(root);
+    while(!q.empty()) {
+      double sum = 0, count = 0;
+      queue<TreeNode*> temp;
+      while (!q.empty()) {
+        TreeNode *n = q.front();
+        q.pop();
+        sum += n->val;
+        count++;
+        if (n->left != NULL)
+          temp.push(n->left);
+        if (n->right != NULL)
+          temp.push(n->right);
+      }
+      q = temp;
+      if (!isnan(sum/count)) ans.push_back(sum/count);
+    }
+    return ans;
+  }
+};
+
+int main() {
+  int arr[] = {3,9,20,15,7};
+  int n = sizeof(arr)/sizeof(arr[0]);
+  TreeNode *root = insertLevelOrder(arr, root, 0, n);
+
+  Solution s;
+  vector<double> r = s.averageOfLevels(root);
+
+  for (size_t i = 0; i < r.size(); i++) {
+    cout << r[i] << " ";
+  }
+  cout << endl;
+  return 0;
+}