Egbert Lin's Blog

69. Sqrt(x)

Question:

Given a non-negative integer x, compute and return the square root of x.

Since the return type is an integer, the decimal digits are truncated, and only the integer part of the result is returned.

67. Add Binary

Question:

Given two binary strings a and b, return their sum as a binary string.

66. Plus One

Question:

Given a non-empty array of decimal digits representing a non-negative integer, increment one to the integer.

The digits are stored such that the most significant digit is at the head of the list, and each element in the array contains a single digit.

You may assume the integer does not contain any leading zero, except the number 0 itself.

53. Maximum Subarray

Question:

Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.

Follow up: If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.

Visual Studio Code installation and run it from Terminal on macOS

Background

Visual Studio Code is a free source-code editor made by Microsoft for Windows, Linux and macOS.
Features include support for debugging, syntax highlighting, intelligent code completion, snippets, code refactoring, and embedded Git. Users can change the theme, keyboard shortcuts, preferences, and install extensions that add additional functionality.

Installation

1. Download Visual Studio Code for macOS directly.
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38. Count and Say

Question:

To determine how you "say" a digit string, split it into the minimal number of groups so that each group is a contiguous section all of the same character. Then for each group, say the number of characters, then say the character. To convert the saying into a digit string, replace the counts with a number and concatenate every saying.

35. Search Insert Position

Question:

Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

28. Implement strStr()

Question:

Implement strStr().

Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
Clarification: What should we return when needle is an empty string? This is a great question to ask during an interview.

For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C's strstr() and Java's indexOf().

27. Remove Element

Question:

Given an array nums and a value val, 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 array in-place with O(1) extra memory.

The order of elements can be changed. It doesn't matter what you leave beyond the new length.

26. Remove Duplicates from Sorted Array

Question:

Given a sorted array nums, remove the duplicates in-place such that each element appears only once and returns the new length.

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.