摘要： path sum 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. For example : Given the below the binary ... 阅读全文

摘要： Reverse String Write a function that takes a string as input and returns the string reversed. Example: Given s = "hello", return "olleh" c++ solution1: class solution1: { public: str... 阅读全文