Peggy_Chang的博客

Description: Given an array nums, write a function to move all 0’s to the end of it while maintaining the relative order of the non-zero elements.

Description: Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.For example, “A man, a plan, a canal: Panama” is a palindrome. “race a ca...

Description: Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.For example, Given [3,2,1,5,6,4] and k = 2...

Description: Given four lists A, B, C, D of integer values, compute how many tuples (i, j, k, l) there are such that A[i] + B[j] + C[k] + D[l] is zero.To make problem a bit easier, all A, B, C, D h...

Description: Given two arrays, write a function to compute their intersection.Example: Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2, 2].Note: Each element in the result should appear a...

Description: Given two arrays, write a function to compute their intersection.Example: Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2].Note: Each element in the result must be unique. T...

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

Description: Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue.Here, we will use t...

Description: You’re given strings J representing the types of stones that are jewels, and S representing the stones you have. Each character in S is a type of stone you have. You want to know how m...

144. Binary Tree Preorder TraversalDescription: Given a binary tree, return the preorder traversal of its nodes’ values.For example: Given binary tree [1,null,2,3], 1 \ 2 / ...

Description: Follow up for “Remove Duplicates”: What if duplicates are allowed at most twice? 由于follow up Problem 26，因此还是要求in-place。Example: Given sorted array nums = [1,1,1,2,2,3], 仍旧是排好序的数组 ...

Description: Given a sorted array, remove the duplicates in-place such that each element appear only once and return the new length.Do not allocate extra space for another array, you must do this b...

Description: Given an array and a value, remove all instances of that value in-place and return the new length.Do not allocate extra space for another array, you must do this by modifying the input...

Description: Given n non-negative integers a1, a2, …, an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0...

Description: Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.The function twoSum should return indices of th...

Description: Write a function that takes a string as input and returns the string reversed.Example: Given s = “hello”, return “olleh”.考虑空字符串，也属于reversed string.解法一： 基本思想：对撞指针。 思路：从头从尾分别同时遍历，...