pangzhe_sd的博客

Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n.For example:Given n = 13,Return 6, because digit 1 occurred in the follow

还是递归问题，定义left和right递归调用原函数，直到叶子结点为止。判断两个输入参数的父节点，有三种情况：第一，分别为左右树，父节点为root (第一个if条件)第二，遍历到P和Q时，将其返回给left和right,(第二个if条件)第三，根据left和right的值进行判断，父节点是左边还是右边并返回对应值（第三个if条件）。/** * Definition for

Implement the following operations of a queue using stacks. push(x) -- Push element x to the back of queue. pop() -- Removes the element from in front of queue. peek() -- Get the front element. em

Given two sorted integer arrays nums1 and nums2, merge nums2 intonums1 as one sorted array.Note:You may assume that nums1 has enough space (size that is greater or equal tom + n) to hold a

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