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Given an array of 2n integers, your task is to group these integers into n pairs of integer, say (a1, b1), (a2, b2), ..., (an, bn) which makes sum of 阅读全文
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Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are n 阅读全文
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Initially, there is a Robot at position (0, 0). Given a sequence of its moves, judge if this robot makes a circle, which means it moves back to the or 阅读全文
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The Hamming distance between two integers is the number of positions at which the corresponding bits are different. Given two integers x and y, calcul 阅读全文