LeetCode 77. CombinationsLeetCode-77 Given two integers n and k, return all possible combinations of k numbers out of th

LeetCode 50. PowLeetCode Implement pow(x, n), which calculates x raised to the power n. Example 1:Input: x = 2.00000, n

LeetCode 18. 4SumLeetCode-18 Given an array nums of n integers, return an array of all the unique quadruplets [nums[a],

LeetCode 150. Evaluate Reverse Polish NotationLeetCode-150 Evaluate the value of an arithmetic expression in Reverse Pol

LeetCode 1047. Remove All Adjacent Duplicates In StringLeetCode-1047 You are given a string s consisting of lowercase En

LeetCode 17. Letter Combinations of a Phone NumberLeetCode-17 Given a string containing digits from 2-9 inclusive, retur

LeetCode 15. 3SumLeetCode-15 Given an integer array nums, return all the triplets [nums[i], nums[j], nums[k]] such that

二阶常系数齐次线性微分方程的形式为： a{y}^{\prime \prime}+b{y}^{\prime}+cy=0由于是二阶线性微分方程，所以它有两个解，记为$y_1, y_2$它的特征方程为： ar^2+br+c=0写出微分方程的特征方

LeetCode 202. Happy NumberLeetCode Write an algorithm to determine if a number n is happy. A happy number is a number de

LeetCode 349. Intersection of Two ArraysLeetCode-349 Given two integer arrays nums1 and nums2, return an array of their

LeetCode 242. Valid AnagramLeetCode-242 Given two strings s and t, return true if t is an anagram of s, and false otherw

LeetCode 485. Max Consecutive OnesLeetCode-485 Given a binary array nums, return the maximum number of consecutive 1'