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题目： Given a string, determine if a permutation of the string could form a palindrome. For example,"code" -> False, "aab" -> True, "carerac" -> True. H 阅读全文
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题目： There are a row of n houses, each house can be painted with one of the k colors. The cost of painting each house with a certain color is different 阅读全文
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题目： Write a program to find the n-th ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 1, 2, 3, 4, 阅读全文