Created
May 19, 2013 18:03
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Given a string of brackets/parantheses, check if the string is valid. ex: [[]] is valid, ][][ is not valid. How would you solve if the parantheses could be of different types like {, [, (?
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| function validBrackets (brackets) { | |
| var counts = { | |
| '(': 0, | |
| '[': 0, | |
| '{': 0 | |
| }, | |
| pairs = { | |
| ')': '(', | |
| ']': '[', | |
| '}': '{' | |
| }, | |
| i = 0, | |
| n = brackets.length, | |
| bracket, | |
| stack = []; | |
| for (; i < n; ++i) { | |
| bracket = brackets[i]; | |
| switch (bracket) { | |
| case '(': | |
| case '[': | |
| case '{': | |
| stack.push(bracket); | |
| counts[bracket]++; | |
| break; | |
| case ')': | |
| case ']': | |
| case '}': | |
| if (stack[stack.length - 1] !== pairs[bracket]) { | |
| return false; | |
| } | |
| stack.pop(); | |
| break; | |
| default: | |
| return false; | |
| } | |
| } | |
| return !stack.length; | |
| } |
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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>Valid Brackets</title> | |
| </head> | |
| <body> | |
| <h1>Valid Brackets</h1> | |
| <p>Given a string of brackets/parantheses, check if the string is valid.</p> | |
| <p>ex: [[]] is valid, ][][ is not valid.</p> | |
| <p>How would you solve if the parantheses could be of different types like {, [, (?</p> | |
| </body> | |
| <script src="validBrackets.js"></script> | |
| <script> | |
| var isTrue = validBrackets('[[]]'), | |
| isFalse = validBrackets('][]['), | |
| isCrazy = validBrackets('{[()()]}([{}]){}'); | |
| console.log(isTrue, isFalse, isCrazy); // true, false, true | |
| </script> | |
| </html> | |
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//Given a string of brackets/parantheses/curly braces, check if the string is valid.
function isValidString(str) {
var strArr = str.split('');
var matches = {'}' : '{', ']' : '[', ')' : '('};
var stack = new Array();
for (var i=0; i<strArr.length; i++) {
var char= strArr[i];
if (Object.values(matches).includes(char)) {
//opener
stack.push(char);
} else if (Object.keys(matches).includes(char)) {
//closer
if (stack[stack.length-1] !== matches[char]) {
return false;
} else {
stack.pop(char);
}
}
}
return !stack.length;
}
alert('the string is valid: ' + isValidString('{[()()]}([{}]){}'));