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Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacen 阅读全文
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Given a binary tree, return all root-to-leaf paths. For example, given the following binary tree: All root-to-leaf paths are: 阅读全文
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Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example:Given the below binary tree and sum 阅读全文
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Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. F 阅读全文
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Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as a binary tree in which the dept 阅读全文
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Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest l 阅读全文
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Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest l 阅读全文
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Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining. 阅读全文
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Given a binary tree, return the postorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, return [3,2,1]. Note: Recursive sol 阅读全文
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Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, return [1,2,3]. Note: Recursive solu 阅读全文