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可以想象有一个无限大的水罐，如果我们有两个杯子x和y，那么原来的问题等价于是否可以通过往里面注入或倒出水从而剩下z。 z =? m*x + n*y 如果等式成立，那么z%gcd(x,y) == 0。 阅读全文
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Numbers can be regarded as product of its factors. For example, Write a function that takes an integer n and return all possible combinations of its f 阅读全文
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Given an integer array with all positive numbers and no duplicates, find the number of possible combinations that add up to a positive integer target. 阅读全文
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Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be 阅读全文
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Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each num 阅读全文
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Given a set of candidate numbers (C) (without duplicates) and a target number (T), find all unique combinations in C where the candidate numbers sums 阅读全文
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Given a binary search tree, write a function kthSmallest to find the kth smallest element in it. Note: You may assume k is always valid, 1 ≤ k ≤ BST's 阅读全文