我已经实现了removeSelection一个从左派堆中删除特定节点的函数。该代码通过一个哈希表定位节点，该哈希表跟踪已插入堆中的键。然后该节点被渗透到堆的根deleteMin并被调用以删除它。代码似乎在调用的swapWithParent函数中失败了percolateUp，它会产生一个段错误。
这是要从堆上的 main 调用的函数：
bool removeSelection( const Comparable & x )
{
LeftistNode * temp = locateNode( x ); //find the node with the item
if(temp == NULL)
return false;
//percolate that node to the top
percolateUp(temp);
//delete the root
int derp = 0; //deleteMin requires an int be passed
deleteMin(derp);
return true;
}
percolateUp功能：
void percolateUp( LeftistNode * t )
{
if(t != NULL)
{
while(t != root)
{
t = swapWithParent(t->parent, t);
}
}
}
swapWithParent功能：
//swap h2 with its parent h1
//return pointer to h2's new location
LeftistNode * swapWithParent(LeftistNode * h1, LeftistNode * h2)
{
//if h2 is its parent's left child
if(h2 == h1->left)
{
LeftistNode *temp = new LeftistNode(h2->element, -1, h1->parent, h1->left, h1->right, h1->npl); //clone h1 and store as a temp
temp->lines = h2->lines;
//update all pointers
h1->parent = h2;
if(h1->right != NULL)
h1->right->parent = h2;
h1->left = h2->left;
h1->right = h2->right;
h2 = temp;
return h2;
}
else
{
LeftistNode *temp = new LeftistNode(h2->element, -1, h1->parent, h1->left, h1->right, h1->npl); //clone h1 and store as a temp
temp->lines = h2->lines;
//update all pointers
h1->parent = h2;
if(h1->left != NULL)
h1->left->parent = h2;
h1->left = h2->left;
h1->right = h2->right;
h2 = temp;
return h2;
}
}
是否有任何地方我可能会取消引用 NULL 指针？我已经检查过了，但我似乎找不到错误。