摘要： 根部到叶子节点路径之和为某值，递归 阅读全文

摘要： 递归，注意结果的三重判断 阅读全文

摘要： The basic idea is that, for example, nums = [1,2,3,4,5,6,7] and k = 3, first we reverse [1,2,3,4,5,6,7], it becomes[7,6,5,4,3,2,1]; then we reverse[7, 阅读全文