feat: add cpp solution to lcof2 problem: NO.045 (doocs#566)

* feat: add cpp solution to lcof2 problem: NO.045

* feat: add cpp solution to lcof2 problem: NO.045 use queue

* format code

Co-authored-by: willrlzhang <willrlzhang@tencent.com>
Co-authored-by: MaoLongLong <382084620@qq.com>

Author: 3 people

lcof2/剑指 Offer II 045. 二叉树最底层最左边的值/README.md

@@ -64,6 +64,49 @@
 
 ```
 
+### **C++**
+
+```cpp
+class Solution {
+public:
+    int findBottomLeftValue(TreeNode* root) {
+        if (!root)
+        {
+            return 0;
+        }
+
+        int res = root->val;
+        queue<TreeNode*> que;
+        que.push(root);
+        while (!que.empty())
+        {
+            int size = que.size();
+            for (int i = 0; i < size; i++)
+            {
+                TreeNode* ptr = que.front();
+                que.pop();
+                if (i == 0)
+                {
+                    res = ptr->val;
+                }
+
+                if (ptr->left)
+                {
+                    que.push(ptr->left);
+                }
+
+                if (ptr->right)
+                {
+                    que.push(ptr->right);
+                }
+            }
+        }
+
+        return res;
+    }
+};
+```
+
 ### **...**
 
 ```

lcof2/剑指 Offer II 045. 二叉树最底层最左边的值/Solution.cpp

@@ -0,0 +1,38 @@
+class Solution {
+public:
+    int findBottomLeftValue(TreeNode* root) {
+        if (!root)
+        {
+            return 0;
+        }
+
+        int res = root->val;
+        queue<TreeNode*> que;
+        que.push(root);
+        while (!que.empty())
+        {
+            int size = que.size();
+            for (int i = 0; i < size; i++)
+            {
+                TreeNode* ptr = que.front();
+                que.pop();
+                if (i == 0)
+                {
+                    res = ptr->val;
+                }
+
+                if (ptr->left)
+                {
+                    que.push(ptr->left);
+                }
+
+                if (ptr->right)
+                {
+                    que.push(ptr->right);
+                }
+            }
+        }
+
+        return res;
+    }
+};