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/******************************** Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. For example, given n = 3, a solution set is: "((())

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). 从外圈往里旋转 void rotate(vector > &matrix) { int size = matrix.size(); int left = 0, right = size

Given a binary tree, return the postorder traversal of its nodes' values. For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [3,2,1]. vector postorderTrav