摘要：
We are given head, the head node of a linked list containing unique integer values. We are also given the list G, a subset of the values in the linked 阅读全文
摘要：
Give a string s, count the number of non-empty (contiguous) substrings that have the same number of 0's and 1's, and all the 0's and all the 1's in th 阅读全文
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X is a good number if after rotating each digit individually by 180 degrees, we get a valid number that is different from X. Each digit must be rotate 阅读全文
摘要：
Implement a MapSum class with insert, and sum methods. For the method insert, you'll be given a pair of (string, integer). The string represents the k 阅读全文