Shorten an || or if statement in Golang - go

Learning Golang and was wondering if there is a shorter way to write this
if tiletype == 0 || tiletype == 2 {
levelmap[passage1block] = "wall"
} else {
levelmap[passage1block] = "floor"
}
Was thinking this would be the way though it does not work
if tiletype ==0,2 {
levelmap[passage1block] = "wall"
} else {
levelmap[passage1block] = "floor"
}

You can write a switch-case statement:
switch tiletype {
case 0,2: levelmap[passage1block]="wall"
default: levelmap[passage1block]="floor"
}

Related

Troubles with for loop and Range

var colRange = getRange("Sheet1!G2:G200")
logger.log(colRange)
logger.log(colRange[0])
for(var i = 0; i < colRange.length; i++) {
if(activeCell.getColumn() == 7 && activeCell.getRow() == colRange[i] && ss.getActiveSheet().getName()=="Sheet1") {
newValue=e.value;
oldValue=e.oldValue;
if(!e.value) {
activeCell.setValue("");
}
else {
if (!e.oldValue) {
activeCell.setValue(newValue);
}
else {
activeCell.setValue(oldValue+', '+newValue);
}
}
}
}
Could anybody help with the for loop. Need it to check every row of column G to allow multiple drop down selections. If I replace colRange[i] with the specific row it does work. I assume I need to loop through each range G2, G3, G4, etc
Please explain what you are trying to
It's hard to figure out what you are trying to accomplish with you code but this is my best guess
function onEdit(e) {
const sh = e.range.getSheet();
if (e.range.columnStart == 7 && e.range.rowStart > 1 && sh.getName() == "Sheet1") {
if (!e.value) {
e.range.setValue("");//doesn't make sense it's already null
} else if (!e.oldValue) {
e.range.setValue(e.value);
} else {
e.range.setValue(oldValue + ', ' + newValue);
}
}
}

Adding a trailing Stop loss to an expert advisor using MQL5

Hi I'm new to MQL5 and I wanted to add a trailing stop loss to my expert advisor but some reason it does not add. Here is the code:
if(PositionSelect(_Symbol) && UseTrailingStop == true)
{
double TrailingStop = (atr[1] * 3) + close[1];
Trail.TrailingStop(_Symbol,TrailingStop,0,0);
}
Please note that close[1] is for the close price of the previous bar and atr[1] is for the value of the average true range. What am i doing wrong?????
There you go: hope this is helpful.
//--- trailing position
for(i=0;i<PositionsTotal();i++)
{
if(Symbol()==PositionGetSymbol(i))
{
if(PositionGetInteger(POSITION_TYPE)==POSITION_TYPE_BUY)
{
sl=MathMax(PositionGetDouble(POSITION_PRICE_OPEN)+Spread*_Point,Bid-SL*_Point);
if(sl>PositionGetDouble(POSITION_SL) && (Bid-StopLevel*_Point-Spread*_Point)>PositionGetDouble(POSITION_PRICE_OPEN))
{
request.action = TRADE_ACTION_SLTP;
request.symbol = _Symbol;
request.sl = NormalizeDouble(sl,_Digits);
request.tp = PositionGetDouble(POSITION_TP);
OrderSend(request,result);
if(result.retcode==10009 || result.retcode==10008) // request executed
Print("Moving Stop Loss of Buy position #",request.order);
else
{
Print(ResultRetcodeDescription(result.retcode));
return;
}
return;
}
}
if(PositionGetInteger(POSITION_TYPE)==POSITION_TYPE_SELL)
{
sl=MathMin(PositionGetDouble(POSITION_PRICE_OPEN)-Spread*_Point,Ask+SL*_Point);
if(sl<PositionGetDouble(POSITION_SL) && (PositionGetDouble(POSITION_PRICE_OPEN)-StopLevel*_Point-Spread*_Point)>Ask)
{
request.action = TRADE_ACTION_SLTP;
request.symbol = _Symbol;
request.sl = NormalizeDouble(sl,_Digits);
request.tp = PositionGetDouble(POSITION_TP);
OrderSend(request,result);
if(result.retcode==10009 || result.retcode==10008) // request executed
Print("Moving Stop Loss of Sell position #",request.order);
else
{
Print(ResultRetcodeDescription(result.retcode));
return;
}
return;
}
}
}
}

Kotlin Cannibals and Missionaries Algorithm - How to convert to full FP

Any suggestions on how to improve the following code to make it more Functional Programming oriented. Specifically how to remove the MutableList which signifies historical states. There are two data classes: Bank, which represents a riverbank (number of missionaries and number of cannibals currently on the bank) and BankState which represents a historical state of the two banks (the source bank, target bank and boatAtSource - a boolean which indicates whether the boat is currently at the source or target bank). overloaded operator function plus adds missionaries and cannibals to a riverbank and function minus removes them from a riverbank. The boat function is the one which carries the most heft. You can call the following algorithm from fun main (app.kt) as such:
app.kt
fun main(args:Array<String>) {
val source:Bank = Bank(3,3)
val target:Bank = Bank()
source boat target
}
Bank.kt
data class Bank(val missionaries:Int=0,val cannibals:Int=0)
data class BankState(val sourceTarget:Pair<Bank,Bank>,val boatAtSource:Boolean)
operator fun Bank.plus(b:Pair<Int,Int>):Bank = Bank(this.missionaries+b.first,this.cannibals+b.second)
operator fun Bank.minus(b:Pair<Int,Int>):Bank = Bank(this.missionaries-b.first,this.cannibals-b.second)
infix fun Bank.boat(target:Bank):List<BankState> {
val begin = Pair(this,target)
val history = mutableListOf<BankState>(BankState(begin,true))
boat(begin,true,this.missionaries,this.cannibals,history)
return history
}
fun boat(sourceTarget:Pair<Bank,Bank>,
boatAtSource:Boolean,
totalMissionaries:Int,
totalCannibals:Int,
history:MutableList<BankState>):Boolean {
if(sourceTarget.first.cannibals+sourceTarget.second.cannibals==totalCannibals &&
sourceTarget.first.missionaries + sourceTarget.second.missionaries==totalMissionaries &&
sourceTarget.first.cannibals>=0 &&
sourceTarget.first.missionaries>=0 &&
sourceTarget.second.cannibals>=0 &&
sourceTarget.second.missionaries>=0 &&
(sourceTarget.first.missionaries==0 || sourceTarget.first.missionaries>=sourceTarget.first.cannibals) &&
(sourceTarget.second.missionaries==0 || sourceTarget.second.missionaries >= sourceTarget.second.cannibals)) {
if(sourceTarget.second.missionaries==totalMissionaries &&
sourceTarget.second.cannibals==totalCannibals) {
history.forEach(::println)
return true
} else {
val deltas = listOf(Pair(0,1),Pair(1,1),Pair(1,0),Pair(2,0),Pair(0,2))
val comparator = object : Comparator<Pair<Pair<Boolean,Int>,Pair<Bank,Bank>>> {
override fun compare(arg1:Pair<Pair<Boolean,Int>,Pair<Bank,Bank>>,arg2:Pair<Pair<Boolean,Int>,Pair<Bank,Bank>>):Int {
if(arg1.first.first && arg2.first.first) {
return if(arg1.first.second<arg2.first.second) -1 else if(arg1.first.second>arg2.first.second) 1 else 0
} else if(arg1.first.first){
return 1
} else if(arg2.first.first) {
return -1
}
return 0
}
}
val result = deltas.map{
checkNext(it.first,it.second,totalMissionaries,totalCannibals,history,sourceTarget,boatAtSource)
}.maxWith(comparator)
if(result?.first?.first!=null && result.first.first) {
history.add(BankState(result.second,!boatAtSource))
return true;
}
}
}
return false
}
fun checkNext(missionariesDelta:Int,
cannibalsDelta:Int,
totalMissionaries:Int,
totalCannibals:Int,
history:MutableList<BankState>,
sourceTarget:Pair<Bank,Bank>,
boatAtSource:Boolean):Pair<Pair<Boolean,Int>,Pair<Bank,Bank>> {
val nextSrcTgt = if(boatAtSource) Pair(sourceTarget.first-Pair(missionariesDelta,cannibalsDelta),sourceTarget.second+Pair(missionariesDelta,cannibalsDelta))
else Pair(sourceTarget.first+Pair(missionariesDelta,cannibalsDelta),sourceTarget.second-Pair(missionariesDelta,cannibalsDelta))
val bankState:BankState = BankState(nextSrcTgt,!boatAtSource)
if(!history.contains(bankState)) {
history.add(bankState)
val combo2:Boolean = boat(nextSrcTgt,!boatAtSource,totalMissionaries,totalCannibals,history)
val combo2Depth = history.size
history.remove(bankState)
return Pair(Pair(combo2,combo2Depth),nextSrcTgt)
} else {
return Pair(Pair(false,0),nextSrcTgt)
}
}

Order an array of objects by the value of their enums in swift

I have an array of CLBeacon objects which all have a property .proximity.
I want to order the array by this property which contains the CLProximity enum. So I want all objects to be in order IMMEDIATE, NEAR, FAR, UNKNOWN.
Is there a way to do this neatly without resorting to a bunch of if statements?
If you define a (computed read-only) property sortIndex of CLProximity
extension CLProximity {
var sortIndex : Int {
switch self {
case .Immediate:
return 0
case .Near:
return 1
case .Far:
return 2
case .Unknown:
return 3
}
}
}
then you can sort an array of beacons with
let sortedBeacons = sorted(beacons) { $0.proximity.sortIndex < $1.proximity.sortIndex }
If .Unknown is the only CLProximity value that needs
"special treatment" and all other possible values are in the desired
relative order then you can simplify the property definition to
extension CLProximity {
var sortIndex : Int {
return self == .Unknown ? Int.max : rawValue
}
}
You can use custom comparator and sort an array using that ,
You will "say" for all objects that has "unknown" proximity are "bigger" than others
var sortedArray = persons.sortedArrayUsingComparator {
(obj1, obj2) -> NSComparisonResult in
if obj1.proximity.rawValue == obj12.proximity.rawValue {
return NSComparisonResult.OrderedSame
} else if obj1.proximity == .UNKNOWN || obj1.proximity.rawValue > obj12.proximity.rawValue {
return NSComparisonResult.OrderedDescending
}
return NSComparisonResult.OrderedAscending
}
Based on what Julia wrote above I had cobbled this together:
self.beacons = beacons as! [CLBeacon]
var tempBeacons = zip(self.beacons, self.beacons.map({
(b: CLBeacon) -> Int in
if b.proximity == .Immediate {
return 0
} else if b.proximity == .Near {
return 1
} else if b.proximity == .Far {
return 2
} else if b.proximity == .Unknown {
return 3
}
return 0
}))
self.beacons = sorted(tempBeacons, {$0.1 < $1.1}).map({ $0.0 })
Thanks all!
Based on #Martin answer.
You can also create Int enum and assign value to it and then sort it like below.
enum myEnum: Int {
case A = 0
case B = 1
case C = 2
case D = 3
}
let myData : [myEnum:[String]] = [.C:["3"],.D:["4"],.B:["2"],.A:["1"]]
print(myData.first?.key)
let newData = myData.sorted(by: { $0.key.rawValue < $1.key.rawValue })
print(newData.first?.key)
Hope this helps
Swift 5
Now you can just add Comparable to your enum and it respects the order
enum ContainerLevel: Comparable {
case empty
case almostEmpty
case halfFull
case almostFull
case full
}
//Are we running low?
let needMoreCoffee = coffeeMugLevel > .halfFull
print(needMoreCoffee) //true
Link to more Code examples

Basic Recursion, Check Balanced Parenthesis

I've written software in the past that uses a stack to check for balanced equations, but now I'm asked to write a similar algorithm recursively to check for properly nested brackets and parenthesis.
Good examples: () [] ()
([]()[])
Bad examples: ( (] ([)]
Suppose my function is called: isBalanced.
Should each pass evaluate a smaller substring (until reaching a base case of 2 left)? Or, should I always evaluate the full string and move indices inward?
First, to your original question, just be aware that if you're working with very long strings, you don't want to be making exact copies minus a single letter each time you make a function call. So you should favor using indexes or verify that your language of choice isn't making copies behind the scenes.
Second, I have an issue with all the answers here that are using a stack data structure. I think the point of your assignment is for you to understand that with recursion your function calls create a stack. You don't need to use a stack data structure to hold your parentheses because each recursive call is a new entry on an implicit stack.
I'll demonstrate with a C program that matches ( and ). Adding the other types like [ and ] is an exercise for the reader. All I maintain in the function is my position in the string (passed as a pointer) because the recursion is my stack.
/* Search a string for matching parentheses. If the parentheses match, returns a
* pointer that addresses the nul terminator at the end of the string. If they
* don't match, the pointer addresses the first character that doesn't match.
*/
const char *match(const char *str)
{
if( *str == '\0' || *str == ')' ) { return str; }
if( *str == '(' )
{
const char *closer = match(++str);
if( *closer == ')' )
{
return match(++closer);
}
return str - 1;
}
return match(++str);
}
Tested with this code:
const char *test[] = {
"()", "(", ")", "", "(()))", "(((())))", "()()(()())",
"(() ( hi))) (())()(((( ))))", "abcd"
};
for( index = 0; index < sizeof(test) / sizeof(test[0]); ++index ) {
const char *result = match(test[index]);
printf("%s:\t", test[index]);
*result == '\0' ? printf("Good!\n") :
printf("Bad # char %d\n", result - test[index] + 1);
}
Output:
(): Good!
(: Bad # char 1
): Bad # char 1
: Good!
(())): Bad # char 5
(((()))): Good!
()()(()()): Good!
(() ( hi))) (())()(((( )))): Bad # char 11
abcd: Good!
There are many ways to do this, but the simplest algorithm is to simply process forward left to right, passing the stack as a parameter
FUNCTION isBalanced(String input, String stack) : boolean
IF isEmpty(input)
RETURN isEmpty(stack)
ELSE IF isOpen(firstChar(input))
RETURN isBalanced(allButFirst(input), stack + firstChar(input))
ELSE IF isClose(firstChar(input))
RETURN NOT isEmpty(stack) AND isMatching(firstChar(input), lastChar(stack))
AND isBalanced(allButFirst(input), allButLast(stack))
ELSE
ERROR "Invalid character"
Here it is implemented in Java. Note that I've switched it now so that the stack pushes in front instead of at the back of the string, for convenience. I've also modified it so that it just skips non-parenthesis symbols instead of reporting it as an error.
static String open = "([<{";
static String close = ")]>}";
static boolean isOpen(char ch) {
return open.indexOf(ch) != -1;
}
static boolean isClose(char ch) {
return close.indexOf(ch) != -1;
}
static boolean isMatching(char chOpen, char chClose) {
return open.indexOf(chOpen) == close.indexOf(chClose);
}
static boolean isBalanced(String input, String stack) {
return
input.isEmpty() ?
stack.isEmpty()
: isOpen(input.charAt(0)) ?
isBalanced(input.substring(1), input.charAt(0) + stack)
: isClose(input.charAt(0)) ?
!stack.isEmpty() && isMatching(stack.charAt(0), input.charAt(0))
&& isBalanced(input.substring(1), stack.substring(1))
: isBalanced(input.substring(1), stack);
}
Test harness:
String[] tests = {
"()[]<>{}",
"(<",
"]}",
"()<",
"(][)",
"{(X)[XY]}",
};
for (String s : tests) {
System.out.println(s + " = " + isBalanced(s, ""));
}
Output:
()[]<>{} = true
(< = false
]} = false
()< = false
(][) = false
{(X)[XY]} = true
The idea is to keep a list of the opened brackets, and if you find a closing brackt, check if it closes the last opened:
If those brackets match, then remove the last opened from the list of openedBrackets and continue to check recursively on the rest of the string
Else you have found a brackets that close a nerver opened once, so it is not balanced.
When the string is finally empty, if the list of brackes is empty too (so all the brackes has been closed) return true, else false
ALGORITHM (in Java):
public static boolean isBalanced(final String str1, final LinkedList<Character> openedBrackets, final Map<Character, Character> closeToOpen) {
if ((str1 == null) || str1.isEmpty()) {
return openedBrackets.isEmpty();
} else if (closeToOpen.containsValue(str1.charAt(0))) {
openedBrackets.add(str1.charAt(0));
return isBalanced(str1.substring(1), openedBrackets, closeToOpen);
} else if (closeToOpen.containsKey(str1.charAt(0))) {
if (openedBrackets.getLast() == closeToOpen.get(str1.charAt(0))) {
openedBrackets.removeLast();
return isBalanced(str1.substring(1), openedBrackets, closeToOpen);
} else {
return false;
}
} else {
return isBalanced(str1.substring(1), openedBrackets, closeToOpen);
}
}
TEST:
public static void main(final String[] args) {
final Map<Character, Character> closeToOpen = new HashMap<Character, Character>();
closeToOpen.put('}', '{');
closeToOpen.put(']', '[');
closeToOpen.put(')', '(');
closeToOpen.put('>', '<');
final String[] testSet = new String[] { "abcdefksdhgs", "[{aaa<bb>dd}]<232>", "[ff{<gg}]<ttt>", "{<}>" };
for (final String test : testSet) {
System.out.println(test + " -> " + isBalanced(test, new LinkedList<Character>(), closeToOpen));
}
}
OUTPUT:
abcdefksdhgs -> true
[{aaa<bb>dd}]<232> -> true
[ff{<gg}]<ttt> -> false
{<}> -> false
Note that i have imported the following classes:
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
public static boolean isBalanced(String str) {
if (str.length() == 0) {
return true;
}
if (str.contains("()")) {
return isBalanced(str.replaceFirst("\\(\\)", ""));
}
if (str.contains("[]")) {
return isBalanced(str.replaceFirst("\\[\\]", ""));
}
if (str.contains("{}")) {
return isBalanced(str.replaceFirst("\\{\\}", ""));
} else {
return false;
}
}
Balanced Parenthesis (JS)
The more intuitive solution is to use stack like so:
function isBalanced(str) {
const parentesis = {
'(': ')',
'[': ']',
'{': '}',
};
const closing = Object.values(parentesis);
const stack = [];
for (let char of str) {
if (parentesis[char]) {
stack.push(parentesis[char]);
} else if (closing.includes(char) && char !== stack.pop()) {
return false;
}
}
return !stack.length;
}
console.log(isBalanced('{[()]}')); // true
console.log(isBalanced('{[(]]}')); // false
console.log(isBalanced('([()]')); // false
And using recursive function (without using stack), might look something like so:
function isBalanced(str) {
const parenthesis = {
'(': ')',
'[': ']',
'{': '}',
};
if (!str.length) {
return true;
}
for (let i = 0; i < str.length; i++) {
const char = str[i];
if (parenthesis[char]) {
for (let j = str.length - 1; j >= i; j--) {
const _char = str[j];
if (parenthesis[_char]) {
return false;
} else if (_char === parenthesis[char]) {
return isBalanced(str.substring(i + 1, j));
}
}
} else if (Object.values(parenthesis).includes(char)) {
return false;
}
}
return true;
}
console.log(isBalanced('{[()]}')); // true
console.log(isBalanced('{[(]]}')); // false
console.log(isBalanced('([()]')); // false
* As #Adrian mention, you can also use stack in the recursive function without the need of looking backwards
It doesn't really matter from a logical point of view -- if you keep a stack of all currently un-balanced parens that you pass to each step of the recursion, you'll never need to look backwards, so it doesn't matter if you cut up the string on each recursive call, or just increment an index and only look at the current first character.
In most programming languages, which have non-mutable strings, it's probably more expensive (performance-wise) to shorten the string than it is to pass a slightly larger string on the stack. On the other hand, in a language like C, you could just increment a pointer within the char array. I guess it's pretty language-dependent which of these two approaches is more 'efficient'. They're both equivalent from a conceptual point of view.
In the Scala programming language, I would do it like this:
def balance(chars: List[Char]): Boolean = {
def process(chars: List[Char], myStack: Stack[Char]): Boolean =
if (chars.isEmpty) myStack.isEmpty
else {
chars.head match {
case '(' => process(chars.tail, myStack.push(chars.head))
case ')' => if (myStack.contains('(')) process(chars.tail, myStack.pop)
else false
case '[' => process(chars.tail, myStack.push(chars.head))
case ']' => {
if (myStack.contains('[')) process(chars.tail, myStack.pop) else false
}
case _ => process(chars.tail, myStack)
}
}
val balancingAuxStack = new Stack[Char]
process(chars, balancingAuxStack)
}
Please edit to make it perfect.
I was only suggesting a conversion in Scala.
I would say this depends on your design. You could either use two counters or stack with two different symbols or you can handle it using recursion, the difference is in design approach.
func evalExpression(inStringArray:[String])-> Bool{
var status = false
var inStringArray = inStringArray
if inStringArray.count == 0 {
return true
}
// determine the complimentary bracket.
var complimentaryChar = ""
if (inStringArray.first == "(" || inStringArray.first == "[" || inStringArray.first == "{"){
switch inStringArray.first! {
case "(":
complimentaryChar = ")"
break
case "[":
complimentaryChar = "]"
break
case "{":
complimentaryChar = "}"
break
default:
break
}
}else{
return false
}
// find the complimentary character index in the input array.
var index = 0
var subArray = [String]()
for i in 0..<inStringArray.count{
if inStringArray[i] == complimentaryChar {
index = i
}
}
// if no complimetary bracket is found,so return false.
if index == 0{
return false
}
// create a new sub array for evaluating the brackets.
for i in 0...index{
subArray.append(inStringArray[i])
}
subArray.removeFirst()
subArray.removeLast()
if evalExpression(inStringArray: subArray){
// if part of the expression evaluates to true continue with the rest.
for _ in 0...index{
inStringArray.removeFirst()
}
status = evalExpression(inStringArray: inStringArray)
}
return status
}
PHP Solution to check balanced parentheses
<?php
/**
* #param string $inputString
*/
function isBalanced($inputString)
{
if (0 == strlen($inputString)) {
echo 'String length should be greater than 0';
exit;
}
$stack = array();
for ($i = 0; $i < strlen($inputString); $i++) {
$char = $inputString[$i];
if ($char === '(' || $char === '{' || $char === '[') {
array_push($stack, $char);
}
if ($char === ')' || $char === '}' || $char === ']') {
$matchablePairBraces = array_pop($stack);
$isMatchingPair = isMatchingPair($char, $matchablePairBraces);
if (!$isMatchingPair) {
echo "$inputString is NOT Balanced." . PHP_EOL;
exit;
}
}
}
echo "$inputString is Balanced." . PHP_EOL;
}
/**
* #param string $char1
* #param string $char2
* #return bool
*/
function isMatchingPair($char1, $char2)
{
if ($char1 === ')' && $char2 === '(') {
return true;
}
if ($char1 === '}' && $char2 === '{') {
return true;
}
if ($char1 === ']' && $char2 === '[') {
return true;
}
return false;
}
$inputString = '{ Swatantra (() {} ()) Kumar }';
isBalanced($inputString);
?>
It should be a simple use of stack ..
private string tokens = "{([<})]>";
Stack<char> stack = new Stack<char>();
public bool IsExpressionVaild(string exp)
{
int mid = (tokens.Length / 2) ;
for (int i = 0; i < exp.Length; i++)
{
int index = tokens.IndexOf(exp[i]);
if (-1 == index) { continue; }
if(index<mid ) stack .Push(exp[i]);
else
{
if (stack.Pop() != tokens[index - mid]) { return false; }
}
}
return true;
}
#indiv's answer is nice and enough to solve the parentheses grammar problems. If you want to use stack or do not want to use recursive method you can look at the python script on github. It is simple and fast.
BRACKET_ROUND_OPEN = '('
BRACKET_ROUND__CLOSE = ')'
BRACKET_CURLY_OPEN = '{'
BRACKET_CURLY_CLOSE = '}'
BRACKET_SQUARE_OPEN = '['
BRACKET_SQUARE_CLOSE = ']'
TUPLE_OPEN_CLOSE = [(BRACKET_ROUND_OPEN,BRACKET_ROUND__CLOSE),
(BRACKET_CURLY_OPEN,BRACKET_CURLY_CLOSE),
(BRACKET_SQUARE_OPEN,BRACKET_SQUARE_CLOSE)]
BRACKET_LIST = [BRACKET_ROUND_OPEN,BRACKET_ROUND__CLOSE,BRACKET_CURLY_OPEN,BRACKET_CURLY_CLOSE,BRACKET_SQUARE_OPEN,BRACKET_SQUARE_CLOSE]
def balanced_parentheses(expression):
stack = list()
left = expression[0]
for exp in expression:
if exp not in BRACKET_LIST:
continue
skip = False
for bracket_couple in TUPLE_OPEN_CLOSE:
if exp != bracket_couple[0] and exp != bracket_couple[1]:
continue
if left == bracket_couple[0] and exp == bracket_couple[1]:
if len(stack) == 0:
return False
stack.pop()
skip = True
left = ''
if len(stack) > 0:
left = stack[len(stack) - 1]
if not skip:
left = exp
stack.append(exp)
return len(stack) == 0
if __name__ == '__main__':
print(balanced_parentheses('(()())({})[]'))#True
print(balanced_parentheses('((balanced)(parentheses))({})[]'))#True
print(balanced_parentheses('(()())())'))#False

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