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Givenn, how many structurally uniqueBST's(binary search trees) that store values 1...n?For example,Givenn= 3, there are a total of 5 unique BST's. 1... 阅读全文
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A message containing letters fromA-Zis being encoded to numbers using the following mapping:'A' -> 1'B' -> 2...'Z' -> 26Given an encoded message conta... 阅读全文
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Given a 2D matrixmatrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1,col1) and lower right corner (row2,c... 阅读全文
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Given an integer arraynums, find the sum of the elements between indicesiandj(i≤j), inclusive.Example:Given nums = [-2, 0, 3, -5, 2, -1]sumRange(0, 2)... 阅读全文
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Given a linked list, swap every two adjacent nodes and return its head.For example,Given1->2->3->4, you should return the list as2->1->4->3.Your algor... 阅读全文