Merge pull request doocs#312 from Stackingrule/dev

yanglbme · web-flow · commit 0d436daabe29 · 2020-12-18T21:04:52.000+08:00
feat:add Solution.cpp for 0102.Binary Tree Level Order Traversal
diff --git a/solution/0100-0199/0102.Binary Tree Level Order Traversal/Solution.cpp b/solution/0100-0199/0102.Binary Tree Level Order Traversal/Solution.cpp
@@ -0,0 +1,29 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    vector<vector<int>> levelOrder(TreeNode* root) {
+        if (!root) return {};
+        vector<vector<int>> res;
+        queue<TreeNode*> q{{root}};
+        while (!q.empty()) {
+            vector<int> oneLevel;
+            for (int i = q.size(); i > 0; --i) {
+                TreeNode* t = q.front();
+                q.pop();
+                oneLevel.push_back(t->val);
+                if (t->left) q.push(t->left);
+                if (t->right) q.push(t->right);
+            }
+            res.push_back(oneLevel);
+        }        
+        return res;
+    }
+};
