標籤：: HashTable

2017
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Count Primes

Count PrimesCount the number of prime numbers less than a non-negative number, n. 提示 解題應用 HashTable Array Math 規律觀查 Default:123func countPrimes(n int) int {} 解答思路:非常典型的空間換取時間，因為

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Happy Number

Happy NumberWrite an algorithm to determine if a number is “happy”. A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of t

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Single Number

Single NumberGiven an array of integers, every element appears twice except for one. Find that single one. Note: Your algorithm should have a linear runtime complexity. Could you implement it without

2016
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Valid Sudoku

Valid SudokuThe Sudoku board could be partially filled, where empty cells are filled with the character ‘.’. Note: A valid Sudoku board (partially filled) is not necessarily solvable. Only the fille

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Two Sum

Two SumGiven an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution. Exmaple:1234Given nums