1 class Solution
 2 {
 3     public:
 4         int f(TreeNode* root)
 5         {
 6             if(!root) return 0;
 7             return f(root->left)+f(root->right)+1;
 8         }
 9         TreeNode* preorder(TreeNode *root,int x)
10         {
11             if(!root) return NULL;
12             if(root->val==x)
13                 return root;
14             TreeNode *t1 = preorder(root->left,x);
15             TreeNode *t2 = preorder(root->right,x);
16             if(t1) return t1;
17             else if(t2) return t2;
18             return NULL;
19         }
20         bool btreeGameWinningMove(TreeNode* root, int n, int x)
21         {
22             TreeNode* t = preorder(root,x);
23             int k1 = f(t->left);
24             int k2 = f(t->right);
25             if(max(2*k1,2*k2)>n || n>2*(k1+k2+1))
26                 return true;
27             return false;
28         }
29 };