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Peeking Iterator (M) 题目 Given an Iterator class interface with methods: next() and hasNext(), design and implement a PeekingIterator that support the 阅读全文
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Move Zeroes (E) 题目 Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero element 阅读全文
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Reverse Nodes in k-Group (H) 题目 Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. k is a positive inte 阅读全文
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Swap Nodes in Pairs (M) 题目 Given a linked list, swap every two adjacent nodes and return its head. You may not modify the values in the list's nodes, 阅读全文
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Merge k Sorted Lists (H) 题目 Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. Example: Input: [ 1->4- 阅读全文
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Generate Parentheses (M) 题目 Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. For example, given 阅读全文
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Perfect Squares (M) 题目 Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n. Exa 阅读全文
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Merge Two Sorted Lists (E) 题目 Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of 阅读全文
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Valid Parentheses (E) 题目 Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An inp 阅读全文
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Remove Nth Node From End of List (M) 题目 Given a linked list, remove the n-th node from the end of list and return its head. Example: Given linked list 阅读全文