107 new algo added.

liuyubobobo · liuyubobobo · commit 4b86eacba0ce · 2018-10-16T15:59:09.000-07:00
diff --git a/0107-Binary-Tree-Level-Order-Traversal-II/cpp-0107/CMakeLists.txt b/0107-Binary-Tree-Level-Order-Traversal-II/cpp-0107/CMakeLists.txt
@@ -3,5 +3,5 @@ project(cpp_0107)
 
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
 
-set(SOURCE_FILES main.cpp)
+set(SOURCE_FILES main2.cpp)
 add_executable(cpp_0107 ${SOURCE_FILES})
diff --git a/0107-Binary-Tree-Level-Order-Traversal-II/cpp-0107/main2.cpp b/0107-Binary-Tree-Level-Order-Traversal-II/cpp-0107/main2.cpp
@@ -0,0 +1,74 @@
+/// Source : https://leetcode.com/problems/binary-tree-level-order-traversal-ii/description/
+/// Author : liuyubobobo
+/// Time   : 2018-10-16
+
+#include <iostream>
+
+using namespace std;
+
+#include <iostream>
+#include <vector>
+#include <queue>
+#include <cassert>
+
+using namespace std;
+
+
+/// Definition for a binary tree node.
+struct TreeNode {
+    int val;
+    TreeNode *left;
+    TreeNode *right;
+    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+};
+
+/// BFS
+/// No need to store level information in the queue :-)
+///
+/// Time Complexity: O(n), where n is the number of nodes in the tree
+/// Space Complexity: O(n)
+class Solution {
+public:
+    vector<vector<int>> levelOrderBottom(TreeNode* root) {
+
+        vector<vector<int>> res;
+        if(root == NULL)
+            return res;
+
+        queue<TreeNode*> q;
+        q.push(root);
+        int level_num = 1;
+
+        while(!q.empty()){
+
+            int new_level_num = 0;
+            vector<int> level;
+            for(int i = 0; i < level_num; i ++){
+                TreeNode* node = q.front();
+                q.pop();
+                level.push_back(node->val);
+
+                if(node->left){
+                    q.push(node->left);
+                    new_level_num ++;
+                }
+                if(node->right){
+                    q.push(node->right);
+                    new_level_num ++;
+                }
+            }
+
+            res.push_back(level);
+            level_num = new_level_num;
+        }
+
+        reverse(res.begin(), res.end());
+        return res;
+    }
+};
+
+
+int main() {
+
+    return 0;
+}
