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Question:Given a binary tree, return thelevel ordertraversal of its nodes' values. (ie, from left to right, level by level).For example:Given binary t... 阅读全文
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Question:Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree is symmetric: ... 阅读全文
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Question:Implement the following operations of a queue using stacks.push(x) -- Push element x to the back of queue.pop() -- Removes the element from i... 阅读全文
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Queue接口与List、Set同一级别，都是继承了Collection接口。LinkedList实现了Queue接 口。Queue接口窄化了对LinkedList的方法的访问权限（即在方法中的参数类型如果是Queue时，就完全只能访问Queue接口所定义的方法 了，而不能直接访问 LinkedLi... 阅读全文
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Question:Implement the following operations of a queue using stacks.push(x) -- Push element x to the back of queue.pop() -- Removes the element from i... 阅读全文
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Question:You are climbing a stair case. It takesnsteps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can ... 阅读全文
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Question:Given a binary tree, return all root-to-leaf paths.For example, given the following binary tree: 1 / \2 3 \ 5All root-to-leaf paths ... 阅读全文
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Question:Invert a binary tree. 4 / \ 2 7 / \ / \1 3 6 9to 4 / \ 7 2 / \ / \9 6 3 1Trivia:This problem was inspir... 阅读全文
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Question:Given two binary trees, write a function to check if they are equal or not.Two binary trees are considered equal if they are structurally ide... 阅读全文
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Question:Given a non-negative integernum, repeatedly add all its digits until the result has only one digit.For example:Givennum = 38, the process is ... 阅读全文