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Evaluate the value of an arithmetic expression inReverse Polish Notation.Valid operators are+,-,*,/. Each operand may be an integer or another express... 阅读全文
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Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephon... 阅读全文
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Given a linked list, determine if it has a cycle in it.Follow up:Can you solve it without using extra space?题解：参见http://www.cnblogs.com/sunshineatnoon... 阅读全文
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Given a stringsconsists of upper/lower-case alphabets and empty space characters' ', return the length of last word in the string.If the last word doe... 阅读全文
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Given a collection of numbers, return all possible permutations.For example,[1,2,3]have the following permutations:[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,... 阅读全文