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Problem: Design a logger system that receive stream of messages along with its timestamps, each message should be printed if and only if it is not pri 阅读全文
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Problem: Count the number of prime numbers less than a non-negative number, n. Summary: 判断小于某非负数n的质数个数。 Solution: 用所谓的“刷质数表”的方式先用HashTable记录小于n的所有数是质数 阅读全文
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Problem: Given two strings s and t, determine if they are isomorphic. Two strings are isomorphic if the characters in s can be replaced to get t. All 阅读全文