Delete node in BST

最新推荐文章于 2019-04-20 04:23:21 发布

原创最新推荐文章于 2019-04-20 04:23:21 发布 · 425 阅读

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本文探讨了二叉搜索树(BST)中删除特定值的节点这一复杂问题。文章详细阐述了四种不同情况：叶子节点、仅有右子树的节点、仅有左子树的节点以及同时拥有左右子树的节点。通过递归函数实现，并提供了完整的C++代码示例。

Question: delete the given value in BST.

This question is pretty tricky, to delete a node in BST, there are several cases to consider.

1: The node is one of the leaves, 2: the node only has right children, 3: the node only has left children, 4: the node has left and right children.

code:

TreeNode* deleteTreeNode(TreeNode* root, int val) {
  if(!root) return NULL;
  else {
    if(val < root->val) root->left = deleteTreeNode(root->left, val);
    else if(val > root->val) root->right = deleteTreeNode(root->right, val);
    else {
      // if there is no left child, no right child
      if(root->left == NULL && root->right == NULL) {
        delete root;
        root = NULL;
        return root;
      }
      else if(root->left == NULL) { // if there is no left subtree
        TreeNode* tmp = root;
        root = root->right;
        delete tmp;
        return root;
      } else if(root->right == NULL) { // if there is no right subtree
        TreeNode* tmp = root;
        root = root->right;
        delete tmp;
        return root;
      } else { // two children
        struct TreeNode* tmp = findMin(root->right);
        root->data = tmp->data;
        root->right = deleteTreeNode(root->right, tmp->data);
        return root;
      }
    }
  }
}