如果遇到问题，只需写下来即可：
// First we have a pointer to a node containing element (elm)
// with possible a next element.
// Graphically drawn as:
// p -> [elm] -> ???
tmp = new Node();
// A new node is created. Variable tmp points to the new node which
// currently has no value.
// p -> [elm] -> ???
// tmp -> [?]
tmp.element = p.element;
// The new node Now has the same element as the original.
// p -> [elm] -> ???
// tmp -> [elm]
tmp.next = p.next;
// The new node Now has the same next node as the original.
// p -> [elm] -> ???
// tmp -> [elm] -> ???
p.element = y;
// The original node Now contains the element y.
// p -> [y] -> ???
// tmp -> [elm] -> ???
p.next = tmp;
// The new node is Now the next node from the following.
// p -> [y] -> [elm] -> ???
// tmp -> [elm] -> ???
您已达到要求的效果，但是它可以提高效率，我敢打赌，您现在就可以了解自己。
写这样的东西更清晰：
tmp = new Node();
tmp.element = y;
tmp.next = p;
p = tmp;
如果p不可变，那当然不起作用。但是，如果p == NULL，则您的算法将失败。
但是我要说的是，如果您对算法有疑问，只需写下效果即可。尤其是对于树和链表，您需要确保所有指针都指向严格的方向，否则会造成混乱。
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