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Problem : Reverse a singly linked list. Example: Follow up: A linked list can be reversed either iteratively or recursively. Could you implement both? 阅读全文
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Problem : Given a matrix which is sorted in non increasing order both row wise and column wise. Return the number of negative numbers in . Example 1: 阅读全文
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Problem : Implement FreqStack, a class which simulates the operation of a stack like data structure. FreqStack has two functions: push(int x), which p 阅读全文