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题目: Implement the following operations of a stack using queues. push(x) -- Push element x onto stack. pop() -- Removes the element on top of the stack 阅读全文
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题目： Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and 阅读全文
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题目： Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the 阅读全文
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题目： Reverse a singly linked list. 链接： http://leetcode.com/problems/reverse-linked-list/ 2/25/2017, Java 之前的错误：看起来第一遍没有任何问题，但是1->2居然是time limit exceede 阅读全文