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Finding the longest valid parentheses JavaScript
Given a string containing just the characters '(' and ')', we find the length of the longest valid (well-formed) parentheses substring.
A set of parentheses qualifies to be a well-formed parentheses, if and only if, for each opening parentheses, it contains a closing parentheses.
For example −
'(())()' is a well-formed parentheses '())' is not a well-formed parentheses '()()()' is a well-formed parentheses
Example
const str = '(())()(((';
const longestValidParentheses = (str = '') => {
var ts = str.split('');
var stack = [], max = 0;
ts.forEach((el, ind) => {
if (el == '(') {
stack.push(ind);
}
else {
if (stack.length === 0 || ts[stack[stack.length - 1]] == ')'){
stack.push(ind);
}
else {
stack.pop();
};
}
});
stack.push(ts.length);
stack.splice(0, 0, -1);
for (let ind = 0;
ind< stack.length - 1; ind++) {
let v = stack[ind+1] - stack[ind] - 1; max = Math.max(max, v);
};
return max;
}; console.log(longestValidParentheses(str));Output
And the output in the console will be −
6
Updated on: 23-Nov-2020
238 Views
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