What is the reason for the exclusion of square brackets in the reduce()

Question

What is the reason for the exclusion of square brackets in the reduce()

My current code:

var isValid = function(s) {
    let arr = [...s];

    arr.reduce((acc, cur) => {
        console.log(`arr in reduce: ${arr}`);
        console.log(`acc: ${acc}`);
        console.log(`cur: ${cur}`);
        if ((acc && cur)
        && (
            (acc === '(' && cur === ')')
            || (acc === '{' && cur === '}')
            || (acc === '[' && cur === ']')
        )) {
            arr.splice(arr.indexOf(acc), 2);
            console.log(`arr after splice: ${arr}`);
            return arr;
        }
        else {
            console.log(`else statement: ${cur}`);
            return cur;
        }
    });

    return arr.length === 0 ? true : false;
};

console.log(isValid("()[]{}"));

Requirements for the code to return true:

Open brackets must be closed by the corresponding type of brackets.
Open brackets must be closed in the correct sequence.

Issue with my code when tested with "()[]{}": it consistently returns [,], and I am unsure why. I have attempted regex and ASCII conversions for square brackets without success.

javascript arrays algorithm brackets

Answer 1

Answer №1

To determine the validity of a string containing opening and closing characters, create a stack to store expected closing characters when encountering open characters.

If an open character is found, push the corresponding closing character to the stack. Otherwise, compare the popped value from the stack with the current character.

var isValidString = function([...chars]) {
        var stack = [],
            openPairs =  { '(': ')', '[': ']', '{': '}' };
        return chars.every(char => char in openPairs ? stack.push(openPairs[char]) : char === stack.pop())
            && !stack.length;
    };

console.log(isValidString("()[]{}"));
console.log(isValidString("(({}[()]))[]{}"));
console.log(isValidString("()[]{}}"));
console.log(isValidString("["));

Answer 2

To determine the validity of a string containing opening and closing characters, create a stack to store expected closing characters when encountering open characters.

If an open character is found, push the corresponding closing character to the stack. Otherwise, compare the popped value from the stack with the current character.

var isValidString = function([...chars]) {
        var stack = [],
            openPairs =  { '(': ')', '[': ']', '{': '}' };
        return chars.every(char => char in openPairs ? stack.push(openPairs[char]) : char === stack.pop())
            && !stack.length;
    };

console.log(isValidString("()[]{}"));
console.log(isValidString("(({}[()]))[]{}"));
console.log(isValidString("()[]{}}"));
console.log(isValidString("["));

Answer 3

Answer №2

After performing the splice operation, it is important to note that the length of the array changes. Consequently, when checking the logs, you will observe that [,] is being skipped in the tests due to this modification (the index values in the reduce steps no longer correspond to the array elements). To address this issue, it is advisable to work with a copy of the original array rather than manipulating the array directly during splicing operations.

Furthermore, it should be noted that the current code implementation may not handle nested parenthesis or brackets correctly. Also, caution must be exercised while using indexOf to locate the value of cur, as it returns the index of the first occurrence which may lead to discrepancies if the code logic is altered.

var isValid = function(s) {
    let arr = [...s], copy = [...s];

    arr.reduce((acc, cur) => {
        console.log(`arr in reduce: ${arr}`);
        console.log(`copy in reduce: ${copy}`);
        console.log(`acc: ${acc}`);
        console.log(`cur: ${cur}`);
        if ((acc && cur)
            && (
                (acc === '(' && cur === ')')
                || (acc === '{' && cur === '}')
                || (acc === '[' && cur === ']')
            )) {
            copy.splice(copy.indexOf(acc), 2);
            console.log(`copy after splice: ${copy}`);
            
            return arr;
        }
        else {
            console.log(`else statement: ${cur}`);
            return cur;
        }
    });

    return copy.length === 0 ? true : false;
};

console.log(isValid("()[]{}"));

Answer 4

After performing the splice operation, it is important to note that the length of the array changes. Consequently, when checking the logs, you will observe that [,] is being skipped in the tests due to this modification (the index values in the reduce steps no longer correspond to the array elements). To address this issue, it is advisable to work with a copy of the original array rather than manipulating the array directly during splicing operations.

Furthermore, it should be noted that the current code implementation may not handle nested parenthesis or brackets correctly. Also, caution must be exercised while using indexOf to locate the value of cur, as it returns the index of the first occurrence which may lead to discrepancies if the code logic is altered.

var isValid = function(s) {
    let arr = [...s], copy = [...s];

    arr.reduce((acc, cur) => {
        console.log(`arr in reduce: ${arr}`);
        console.log(`copy in reduce: ${copy}`);
        console.log(`acc: ${acc}`);
        console.log(`cur: ${cur}`);
        if ((acc && cur)
            && (
                (acc === '(' && cur === ')')
                || (acc === '{' && cur === '}')
                || (acc === '[' && cur === ']')
            )) {
            copy.splice(copy.indexOf(acc), 2);
            console.log(`copy after splice: ${copy}`);
            
            return arr;
        }
        else {
            console.log(`else statement: ${cur}`);
            return cur;
        }
    });

    return copy.length === 0 ? true : false;
};

console.log(isValid("()[]{}"));

What is the reason for the exclusion of square brackets in the reduce()

Answer №1

Answer №2

Similar questions

Unveiling the Mystery: Uncovering the Selected Item in Ionic Checkboxes

Unable to utilize query parameters with an ExpressJS API on localhost

When I navigate using state.go in my controller, the Ionic slide menu fails to appear

Pseudo code example for fetching data from MySQL using PHP associative arrays

Comparing the outcomes of using a custom memset function with char *s = "Hello" versus char s[] = "Hello". Can you explain why one method does not actually set memory but still prints the array?

Incorporate a 'back' button in the tab content of vue-form-wizard

Substitute phrases with hyperlinks using JavaScript (or Ruby)

Creating a Gulpfile.js that efficiently manages a multitude of files spread across various folders

Combining GET and POST requests in ExpressJS on a single route

Calculating the height of a window using JavaScript and Ajax

Ways to incorporate the point count divided by a specified value onto a map

What technique can be used to shift focus to the following text field after clicking a button

Setting a minimum width for an inline element that is not displayed as inline-block

Securely authenticate with Node.js using screen scraping techniques

sophisticated HTML navigation bar

Is there a way to perform unit testing on JavaScript code that runs following the completion of a CSS transitionEnd event

Delivery person receiving biscuit but my internet browser doesn't seem to be getting it when I attempt to retrieve it

What is the best way to parse a text file based on a specific delimiter and then store each element of the resulting array

What is the best way to display a dynamic JSON array in an HTML table?

What are some ways that we can enhance each other's value?