xinyu04

摘要： Given an integer $n$, return the number of prime numbers that are strictly less than $n$. Solution 统计小于 $n$ 的素数个数。这里用欧拉筛来筛素数，$is_prime$ 用来记录该数是否为素数，$p 阅读全文

摘要： A peak element is an element that is strictly greater than its neighbors. Given a $0$-indexed integer array nums, find a peak element, and return its 阅读全文

摘要： Suppose an array of length $n$ sorted in ascending order is rotated between $1$ and $n$ times. For example, the array nums = [0,1,2,4,5,6,7] might bec 阅读全文

摘要： Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary search tree. A height-balanced bi 阅读全文

摘要： Write an efficient algorithm that searches for a value target in an m x n integer matrix matrix. This matrix has the following properties: Integers in 阅读全文