摘要：
Determine if a Sudoku is valid, according to:Sudoku Puzzles - The Rules.The Sudoku board could be partially filled, where empty cells are filled with ... 阅读全文
摘要：
Given a string, we can "shift" each of its letter to its successive letter, for example:"abc" -> "bcd". We can keep "shifting" which forms the sequenc... 阅读全文
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这也能算hard题……Given a string, find the length of the longest substring T that contains at most 2 distinct characters.For example, Given s =“eceba”,T is "... 阅读全文
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Given twosparse matricesAandB, return the result ofAB.You may assume thatA's column number is equal toB's row number.Example:A = [ [ 1, 0, 0], [-1, ... 阅读全文