逆转二叉树

逆转二叉树 代码练手

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#include <iostream> #include <memory> using namespace std;   struct TreeNode{     int val;     shared_ptr<TreeNode> left;     shared_ptr<TreeNode> right; };     void PrintTree(shared_ptr<TreeNode> root) {     if (!root)         return;     cout << root->val << "  ";     PrintTree(root->left);     PrintTree(root->right);     return; }   shared_ptr<TreeNode>  CreateNode(int i) {     shared_ptr<TreeNode> p(new TreeNode());     p->val = i;     return p; }   void InsertNode(shared_ptr<TreeNode>& root,int i) {     if (!root)     {         root = CreateNode(i);         return;     }     if (i > root->val)     {         InsertNode(root->right, i);     }     else if (i < root->val)     {         InsertNode(root->left, i);     }     else if (i == root->val)         return;     return; }     shared_ptr<TreeNode> InvertTree(shared_ptr<TreeNode>& root ) {     if (!root)         return root;     shared_ptr<TreeNode> tmp = root->left;     root->left = InvertTree(root->right);     root->right = InvertTree(tmp);     return root; }     int main() {     shared_ptr<TreeNode> root = CreateNode(4);     InsertNode(root, 2);     InsertNode(root, 7);     InsertNode(root, 1);     InsertNode(root, 3);     InsertNode(root, 6);     InsertNode(root, 9);       PrintTree(root);       InvertTree(root);     cout << endl;     PrintTree(root);       return 0; }

　　输出:

4 2 1 3 7 6 9
4 7 9 6 2 3 1