GROKKING NOTES

I liked the way Grokking the coding interview organized problems into learnable patterns. However, the course is expensive and the majority of the time the problems are copy-pasted from leetcode. As the explanations on leetcode are usually just as good, the course really boils down to being a glorified curated list of leetcode problems.

So below I made a list of leetcode problems that are as close to grokking problems as possible.

Pattern: Sliding Window

collegian / groupBy.js

Created October 14, 2020 22:24 — forked from robmathers/groupBy.js

A more readable and annotated version of the Javascript groupBy from Ceasar Bautista (https://stackoverflow.com/a/34890276/1376063)

	var groupBy = function(data, key) { // `data` is an array of objects, `key` is the key (or property accessor) to group by
	// reduce runs this anonymous function on each element of `data` (the `item` parameter,
	// returning the `storage` parameter at the end
	return data.reduce(function(storage, item) {
	// get the first instance of the key by which we're grouping
	var group = item[key];

	// set `storage` for this instance of group to the outer scope (if not empty) or initialize it
	storage[group] = storage[group] \|\| [];

collegian / iTerm2.md

Created October 2, 2020 15:38 — forked from soifou/iTerm2.md

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collegian / Decode.java

Last active October 4, 2019 11:18

Decode

	package lc.dp;

	import java.util.ArrayList;
	import java.util.List;

	public class Decode
	{
	public int numDecodings(String s)
	{
	if(s.equals("0"))

collegian / GroupAnagrams.java

Created September 24, 2019 17:55

Group anagrams sans sorting

	void groupAnagrams(String[] str)
	{
	Map<String,List<String>> lst = new HashMap<String, List<String>>();
	for(String s:str)
	{
	int[] charCnt = new int[26];
	for(char x:s.toCharArray())
	{
	charCnt[x-'a']++;
	}

collegian / FindRectangleZeros.js

Created June 2, 2019 22:12

Wfr find all rectangle containing zeros in an image


	var rectangle = function findRectangle(image)
	{
	var indexSeen = new Set();
	var allResults = [];
	for(let i=0;i<image.length;i++)
	{
	for(let j=0;j<image.length;j++)
	{
	if(image[i][j]===0 && !indexSeen.has((image.length*i)+j))

collegian / MakeChangesWays.java

Created October 4, 2018 02:51

Number of ways to make change for an amount using infinite number of coins

	package recursionAndDP;

	import java.util.Arrays;
	import java.util.List;

	public class MakeChangesWays
	{
	// Idea is to construct an array of all the amounts and the ways to reach each of the amounts using each
	// of the existing coins. To reach amount 0 we have 1 way.
	public void makeChange(List<Integer> coins, int n)

collegian / InnerClass.java

Created September 16, 2018 17:16

Inner class and Nested class usage.

	package misc;

	public class InnerClass
	{
	public Inn greet()
	{
	System.out.println("Greetings to you");
	// This is how typically an inner class is instantiated. The other option is
	// to use the enclosing class instance but this is better.
	return new Inn();

collegian collegian

GROKKING NOTES

Pattern: Sliding Window

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