week50

우석/leetcode/average-of-levels-in-binary-tree.cc

@@ -0,0 +1,36 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+class Solution {
+public:
+    vector<double> averageOfLevels(TreeNode* root) {
+        vector<double> result;
+        vector<int> count;
+        average(root, 0, result, count);
+        for (int i = 0; i < result.size(); i++) {
+            result[i] /= count[i];
+        }   
+        return result;
+    }
+
+    void average(TreeNode* node, int level, vector<double> &sum, vector<int> &count) {
+        if (node == nullptr) return;
+        if (level < sum.size()) { 
+            sum[level] += node->val;
+            count[level] += 1;
+        } else {
+            sum.push_back(node->val);
+            count.push_back(1);
+        }
+        average(node->left, level + 1, sum, count);
+        average(node->right, level + 1, sum, count);
+    }
+};