Question

我试图找到树中两个给定值的最低共同祖先。

我的方法是遍历树的左下角，检查各个节点的天气，它们下面都有节点。给出匹配的第一个节点是最低共同祖先。

有谁能告诉我这个功能的错误。

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Answer 1

如果找到结果，您的递归函数应该只返回一个节点。如果找不到结果节点，它应该返回NULL。如果找到节点则中断，否则继续。我会这样做：

node * lca(node * root, int v1,int v2)   //to find the lowest common ancestor 
{
    if(root==NULL)
        return NULL;

    node* ans=NULL;

    // search the left child tree
    ans = lca(root->left,v1,v2); 
    if (ans != NULL)
      return ans; // if you found it you are finished

    // search the right child tree
    ans = lca(root->right,v1,v2);
    if (ans != NULL)
      return ans; // if you found it you are finished

    // test this tree node
    if( (find(root->left,v1)&&find(root->right,v2)) ||
        (find(root->left,v2)&&find(root->right,v1)))
    {
        // If the condition is true, this node is the result
        return root;
    }

    return NULL; // Neither this node nor any subordinate node of this node is the result 
}

在树中找到最低共同祖先时出错

1 个答案: