Develop Reference

How to write a state machine to solve the Count the smiley faces?

I have solved the problem Count the smiley faces:
Given an array (arr) as an argument complete the function countSmileys that should return the total number of smiling faces.
Rules for a smiling face:
Each smiley face must contain a valid pair of eyes. Eyes can be marked as : or ;
A smiley face can have a nose but it does not have to. Valid characters for a nose are - or ~
Every smiling face must have a smiling mouth that should be marked with either ) or D
No additional characters are allowed except for those mentioned.
Valid smiley face examples: :) :D ;-D :~)
Invalid smiley faces: ;( :> :} :]
Example
countSmileys([':)', ';(', ';}', ':-D']); // should return 2;
countSmileys([';D', ':-(', ':-)', ';~)']); // should return 3;
countSmileys([';]', ':[', ';*', ':$', ';-D']); // should return 1;
Note
In case of an empty array return 0. You will not be tested with invalid input (input will always be an array). Order of the face (eyes, nose, mouth) elements will always be the same.
Then when I look through the solutions I find that many people use regexp. Then I want write a state machine to implement regexp and solve this problem. But I failed. This is my code:
function countSmileys(smileys) {
let state = smileyHasValidEye;
return smileys.filter(smiley => {
for (let s of [...smiley]) {
state = state(s);
}
return state === true;
}).length;
}
function smileyHasValidEye(s) {
if (s === ':' || s === ';') {
return smileyHasValidNose;
}
return smileyHasValidEye;
}
function smileyHasValidNose(s) {
if (s === '-' || s === '~') {
return smileyHasValidMouth;
}
return smileyHasValidMouth(s);
}
function smileyHasValidMouth(s) {
if (s === ')' || s === 'D') {
return true;
}
return;
}
console.log(countSmileys([':)', ';(', ';}', ':-D']));
And the error I get is:
state = state(s);
^
TypeError: state is not a function
Then I debugged my code I found the procedure doesn't enter the smileyHasValidNose function. Then I don't know the reason.

The problem is you don't really reset state in between smileys. So the next smiley state will be true which you can't call (it's not a function).
You could use a local variable for state that resets it to the first function (the first step).
function countSmileys(smileys) {
let firstStep = smileyHasValidEye;
return smileys.filter(smiley => {
let state = firstStep;
for (let s of [...smiley]) {
state = state(s);
}
return state === true;
}).length;
}
function smileyHasValidEye(s) {
if (s === ':' || s === ';') {
return smileyHasValidNose;
}
return smileyHasValidEye;
}
function smileyHasValidNose(s) {
if (s === '-' || s === '~') {
return smileyHasValidMouth;
}
return smileyHasValidMouth(s);
}
function smileyHasValidMouth(s) {
if (s === ')' || s === 'D') {
return true;
}
return;
}
console.log(countSmileys([':)', ';(', ';}', ':-D']));
This code however, will error if there's more on the string besides the smiley (or a partial of the smiley).
I would change smileyHasValidMouth to return false if it doesn't detect a smiley. Just to be more consistent here...
function smileyHasValidMouth(s) {
if (s === ')' || s === 'D') {
return true;
}
return false;
}
And adjust your loop to exit early if it finds a value that is not a function.
for (let s of [...smiley]) {
state = state(s);
if(typeof state !== 'function') return state;
}
function countSmileys(smileys) {
let firstStep = smileyHasValidEye;
return smileys.filter(smiley => {
let state = firstStep;
for (let s of [...smiley]) {
state = state(s);
if (typeof state !== 'function') return state;
}
}).length;
}
function smileyHasValidEye(s) {
if (s === ':' || s === ';') {
return smileyHasValidNose;
}
return smileyHasValidEye;
}
function smileyHasValidNose(s) {
if (s === '-' || s === '~') {
return smileyHasValidMouth;
}
return smileyHasValidMouth(s);
}
function smileyHasValidMouth(s) {
if (s === ')' || s === 'D') {
return true;
}
return false;
}
console.log(countSmileys([':~(', ':>', ':D', ':(', ':o>', ';)', ':)']));

How can I stop this from writing a value to all dictionaries? (Javascript)

Intro
So I have stumbled across this problem yesterday, and I've been stumped trying to figure this out myself. I only have this problem with JavaScript.
Problem
I've been creating a programming language with JS since the start of this week, and I was enjoying myself the entire week making it. The problem here is that when I carry dictionaries across functions, it has some problems reading and writing into those dictionaries. When I check the console logs, I see that not just the dictionary in the function was written, but all of the instances of that dictionary were written.
Code
Here is the code to graph.js:
function codeToArray(code) {
let codeArray = {commands:[], vars:{x:{value:0, read_only:true},y:{value:0, read_only:false}}};
let commands = code.split("\n");
for (i = 0; i < commands.length; i++) {
let command = commands[i];
let inputs = command.split(" ");
if (inputs[0].toLowerCase() !== ";") {
// Arithmetics
if (inputs[0].toLowerCase() === "+") { // Addition
codeArray.commands.push({name:"add", variable:inputs[1], value:inputs[2], syntax_id:1});
} else if (inputs[0].toLowerCase() === "-") { // Subtraction
codeArray.commands.push({name:"subtract", variable:inputs[1], value:inputs[2], syntax_id:1});
} else if (inputs[0].toLowerCase() === "*") { // Multiplication
codeArray.commands.push({name:"multiply", variable:inputs[1], value:inputs[2], syntax_id:1});
} else if (inputs[0].toLowerCase() === "/") { // Division
codeArray.commands.push({name:"divide", variable:inputs[1], value:inputs[2], syntax_id:1});
}
// I/O
else if (inputs[0].toLowerCase() === ":") { // Set
codeArray.commands.push({name:"set", variable:inputs[1], value:inputs[2], syntax_id:1});
}
// Conditional Statements
else if (inputs[0].toLowerCase() === "if") { // If Statement
let ifCommand = "";
for (j = 4; j < inputs.length; j++) {
if (j > 4) {
ifCommand += " " + inputs[j];
} else {
ifCommand += inputs[j];
}
}
let ifCommandArray = codeToArray(ifCommand).commands[0];
codeArray.commands.push({name:"if", value1:inputs[1], condition:inputs[2], value2:inputs[3], command:ifCommandArray, syntax_id:2});
}
}
}
return codeArray
}
function parseValue(value, variables) {
let return_value = value;
console.log(value);
console.log(variables);
if (value.charAt(0) === "$") {
let variable_name = return_value.substring(1, value.length);
console.log(variable_name);
let variable = variables[variable_name];
console.log(variable);
if (variable === undefined) {
return_value = NaN;
} else {
return_value = variable.value;
}
} else {
return_value = parseFloat(value);
}
console.log(return_value);
return return_value
}
function runCodeArray(commands, variables) {
for (i = 0; i < commands.length; i++) {
let command = commands[i];
if (command.syntax_id === 1) { // Simple Syntax (Variable Value Syntax)
if (command.name === "add") { // Addition
let variable = variables[command.variable];
if (variable === undefined) {
let error_message = `Variable cannot be found (line ${i+1} ignoring comments)`;
return {commands:commands, variables:variables, return_message:error_message};
}
if (variable.read_only === true) {
let error_message = `A read-only variable was trying to be written (line ${i+1} ignoring comments)`;
return {commands:commands, variables:variables, return_message:error_message};
}
let value = parseValue(command.value, variables);
if (value === NaN) {
let error_message = `The value parameter is invalid (line ${i+1} ignoring comments)`;
return {commands:commands, variables:variables, return_message:error_message};
}
variable.value += value;
} else if (command.name === "set") { // Set
let variable = variables[command.variable];
if (variable === undefined) {
variables[command.variable] = {value:0, read_only:false};
variable = variables[command.variable];
}
if (variable.read_only === true) {
let error_message = `A read-only variable was trying to be written (line ${i+1} ignoring comments)`;
return {commands:commands, variables:variables, return_message:error_message};
}
let value = parseValue(command.value, variables);
if (value === NaN) {
let error_message = `The value parameter is invalid (line ${i+1} ignoring comments)`;
return {commands:commands, variables:variables, return_message:error_message};
}
variable.value = value;
}
}
}
return {commands:commands, variables:variables, return_message:true};
}
var url_string = ...graph.html?pattern=%3A+a+42%0D%0A%3A+b+%24a%0D%0A%3A+c+%24b%0D%0A // window.location.href;
var url = new URL(url_string);
var pattern = url.searchParams.get("pattern");
let codeArray = codeToArray(pattern);
// console.log(codeArray);
let codeArrayOut = runCodeArray(codeArray.commands, codeArray.vars); // Will return true in return_message if everything is good, and will return a string in return_message if an error occurs.
// console.log(codeArrayOut);
if (codeArrayOut.return_message !== true) {
alert("Error: " + codeArrayOut.return_message);
}
Sorry if the code is too long, boring or messy for you to read. Here is the function that's causing the most problems:
function parseValue(value, variables) {
let return_value = value;
console.log(value);
console.log(variables);
if (value.charAt(0) === "$") {
let variable_name = return_value.substring(1, value.length);
console.log(variable_name);
let variable = variables[variable_name];
console.log(variable);
if (variable === undefined) {
return_value = NaN;
} else {
return_value = variable.value;
}
} else {
return_value = parseFloat(value);
}
console.log(return_value);
return return_value
}
Outro
I'm still learning in JavaScript, so I hope that you can solve this problem (because I can't).

JavaScript Recursive function return undefined instead of an array

I have the next function:
function solveSudoku(prev_tab, fila, columna) {
let tab = _.cloneDeep(prev_tab);
let sig_fila = fila;
let sig_col = columna;
if (fila === 8 && columna === 8) {
//console.log(tab);
return tab;
}
if (columna === 8) {
sig_col = 0;
sig_fila = sig_fila + 1
} else {
sig_col = sig_col + 1;
}
if ((tab[fila][columna]) !== '') {
solveSudoku(tab, sig_fila, sig_col)
} else {
for (let num = 1; num <= 9; num++) {
if (numeroValido(tab, num, fila, columna)) {
tab[fila][columna] = num;
//tab.toString();
solveSudoku(tab, sig_fila, sig_col)
}
}
}
}
it returns undefined instead of a 2D array, i already try to add return in every recursive call =>
return solveSudoku( tab, sig_fila, sig_col )
but now that doesn't work either

I'm not really familiar with algorithms for solving sudoku, so I don't know if the algorithm below is correct.
But you need to ensure that the result of the recursion is returned. In my update below, I return the first recursive call. In the loop, I only return it if the recursion successfully found a solution, otherwise the loop continues trying other numbers in the column.
function solveSudoku(prev_tab, fila, columna) {
let tab = _.cloneDeep(prev_tab);
let sig_fila = fila;
let sig_col = columna;
if (fila === 8 && columna === 8) {
//console.log(tab);
return tab;
}
if (columna === 8) {
sig_col = 0;
sig_fila = sig_fila + 1
} else {
sig_col = sig_col + 1;
}
if ((tab[fila][columna]) !== '') {
return solveSudoku(tab, sig_fila, sig_col)
} else {
for (let num = 1; num <= 9; num++) {
if (numeroValido(tab, num, fila, columna)) {
tab[fila][columna] = num;
//tab.toString();
let result = solveSudoku(tab, sig_fila, sig_col);
if (result) { // continue searching if the recursion failed
return result;
}
}
}
}
}

How to make multiple conditions inside single filter

I am trying to make a filter based on checkboxes.
The thing is js ignoring other conditions inside filter when one is active
filterData() {
return this.airlines.filter(x => {
if (this.filters.options.length != 0 || this.filters.airlines.length != 0) {
for (let i = 0; this.filters.options.length > i; i++) {
if (this.filters.options[i] == 0) {
return x.itineraries[0][0].stops == 0;
}
if (this.filters.options[i] == 1) {
return x.itineraries[0][0].segments[0].baggage_options[0].value > 0;
}
}
} else {
return x;
}
})
}
I know that return will stop the current loop, but is there any way to do it correctly?

Update-1: (When to filter record for every case checked OR case)
Replace for loop and all conditions in a single return by && for if and || condition for data:
var chbox = this.filters.options;
return $.inArray(0, chbox) != -1 && x.itineraries[0][0].stops == 0
|| $.inArray(1, chbox) != -1 && x.itineraries[0][0].segments[0].baggage_options[0].value > 0;
Hope this helps !!
$.inArray(value, arr) method will check for each checkboxes and will work for every checked ones .
Update-2 (When to filter record for every case checked AND case)
As per comment below, you are trying to use checkbox on demand so use below code:
var chbox = this.filters.options;
boolean condition = true;
if ($.inArray(0, chbox) != -1) {
conditon = conditon && x.itineraries[0][0].stops == 0;
}
if ($.inArray(1, chbox) != -1) {
conditon = conditon && x.itineraries[0][0].segments[0].baggage_options[0].value > 0;
}
return condition;

Your filter function is returning an object, which ideally should be a boolean value. Please refactor the code as below.
filterData() {
return this.airlines.filter(x => {
let result = false;
if (this.filters.options.length != 0 || this.filters.airlines.length != 0) {
for (let i = 0; this.filters.options.length > i; i++) {
if (this.filters.options[i] == 0) {
result = x.itineraries[0][0].stops == 0;
break;
} else if (this.filters.options[i] == 1) {
result = x.itineraries[0][0].segments[0].baggage_options[0].value > 0;
break;
}
}
}
return result;
})
}

how to change the loop to become a map?

I haven't found a way to change for into a map, so my plan won't use for but want to use maps in each function of this function
variantDefault = (colorId, sizeId) => {
let selected = [];
let i = 0;
if (this.props.index === 0) {
for (i = 0; i < this.props.values.length; i++) {
if (this.props.values[i].id === colorId) {
selected = this.props.values[i];
}
}
}
if (this.props.index === 1) {
for (i = 0; i < this.props.values.length; i++) {
if (this.props.values[i].id === sizeId) {
selected = this.props.values[i];
}
}
}
console.log(selected);
return selected;
};

you can try this way
variantDefault = (colorId, sizeId) => {
let selected = [];
if (this.props.index === 0) {
this.props.values.map((data) => {
if(data.id === colorId){
selected.push(data)
}
})
}
if (this.props.index === 1) {
this.props.values.map((data) => {
if (data.id === sizeId) {
selected.push(data)
}
})
}
console.log(selected);
return selected;
};

You could take Array#find and return the found item.
variantDefault = (colorId, sizeId) => this.props.values.find(
({ id }) => id === [colorId, sizeId][this.props.index]
) || [];

The use of Array.prototype.filter seems more fitting.
variantDefault = (colorId, sizeId) => {
if (this.props.index.isBetween(0, arguments.length, 1)) return [];
var compareTo = arguments[this.props.index];
return this.props.values.filter(item => item.id === compareTo);
};
If you only want to return the last element found (which is what you are doing in your example) then add an Array.prototype.pop call to the filtered array.
You can add the isBetween function by doing:
if (typeof Number.prototype.isBetween !== "function") {
Number.prototype.isBetween = function(start, end, inclusive) {
if (typeof start !== "number" || isNaN(start)) throw Error("Start is not a number");
if (typeof end !== "number" || isNaN(end)) throw Error("End is not a number");
return inclusive ? start <= this && this <= end : start < this && this < end;
};
}