Remove Duplicates from Sorted Lists II @leetcode

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C++ 学习：The C++ Programming Language, 4th Edition
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创业：The Start-up of You: Adapt to the Future, Invest in Yourself, and Transform Your Career

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.

这道题做了好久逻辑还是没对，总是漏掉一些东西，考虑得很复杂，看了别人的代码后有了一些启发。第一，用safeguard，就是在head前面加上一个头结点，避免处理head的情况。最后记得删掉。第二，就是平时可以先用自己复杂的逻辑把代码写出来，再对比别人的看如何把逻辑简化，这样就可以把代码简化，多做几次会形成一种直觉，下一次设计会快很多。