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题目如下： A character is unique in string S if it occurs exactly once in it. For example, in string S = "LETTER", the only unique characters are "L" and " 阅读全文
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题目如下： Given a binary string S (a string consisting only of '0' and '1's) and a positive integer N, return true if and only if for every integer X from 阅读全文
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题目如下： Given an array A of positive integers, A[i]represents the value of the i-th sightseeing spot, and two sightseeing spots i and j have distance j 阅读全文
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题目如下： Given an array A of integers, return true if and only if we can partition the array into three non-emptyparts with equal sums. Formally, we can 阅读全文