Balancing longest balanced sequence array with javascript

Question

How to balance and array the code like
input
1,2,-2,-1,3,4,-3
the output is
4
because 1,2,-2,-1 is balance one rather than 3,4,-3

You must open parentheses must be closed by the same type of parentheses.

this is my code :

var ans, s, temp, n, a;
n = 7;
a = 1,2,-2,-1,3,4,-3;
s = [];
ans = 0;

for (var i = 0, a = n; i < a.length; i += 1) {
if (a[i] > 0) {
s.append(i);
} else {
if (a[i] < 0) {
if (s && a[i] === -a[s.slice(-1)[0]]) {
s.pop();

if (!s) {
temp = -1;
} else {
temp = s.slice(-1)[0];
}

ans = max(ans, i - temp);
} else {
s.append(i);
}
}
}
}

console.log(ans);

please teach me with hard ways not simple ways if can
Thank You

Answer 1

Please try this:

const BalanceSeq = arr => {
let Seq = [];
for(let i = 0; i < arr.length; i++) {
if(arr[i]==-arr[i+1]){
for(let a = 0; a < arr.length/2+1; a++) {
if(arr[i-a]!=-arr[i+1+a]) {
Seq = arr.slice(i-a+1,i+a+1);
break
}
}
}
}
return `Array: [${Seq}] - Length: ${Seq.length}\n`;
}

console.log(BalanceSeq([1,2,-2,-1,3,4,-3]))
console.log(BalanceSeq([7,5,5,1,2,-2,-1,-5,3,4,-3]))
console.log(BalanceSeq([3,-4,1,2,-2,-1,3,4]))
console.log(BalanceSeq([2,3,2,-8,1,3,-3,-1,8,-2,-3,4,1]))

https://code.sololearn.com/WtAIo8flOYXl/?ref=app

Answer 2

if(arr[i]==-arr[i+1]) for finding the center of sequence (like 2,-2 is center)

Answer 3

Jansen Su
I edited my code for must be start by positive (re cheak please)

Answer 4

let x = [1,2,-2,-1,3,4,-3];
console.log(x.reduce((a,b)=> a+b, 0))

Answer 5

@Ipang, the balanced sequence is like 1 2 -2 -1 = balanced sequence that's why the output is 4 because the balance subarray has 4 numbers. If you do like 1 2 -1 -2 this is not balanced. You must have open parentheses must be closed by the same type of parentheses.

Answer 6

@SAN if(arr[i]==-arr[i+1]) what is this statement mean?

for(let a = 0; a < arr.length/2+1; a++) {

at this statement why is the arr.length/2+1 like this?

if(arr[i-a]!=-arr[i+1+a]) {
Seq = arr.slice(i-a+1,i+a+1);
break
}

what does this statement do for the case I know this is for placement and checking the balance but how to explain properly about this statement?

return `Array: [${Seq}] - Length: ${Seq.length}\n`;

what is this mean?

Thank you for the help, I need to understand this more for more experience

Answer 7

@Ipang 1, 2, -2, -1 // longest balanced sub sequence

Answer 8

What was the criteria for a balanced sequence here? is it cause the sequence result in zero? as in 1 + 2 + (-2) + (-1) or is it cause the sequence is palindromic, disregarding sign?

Answer 9

Thanks Jansen Su
I get it now

So your goal was to find the longest balanced sequence or to balance a given sequence. The post's title seem to be asking for how to balance the sequence ...

Answer 10

Yes, I need to learn the way how to implement it without any simple solution, so I can learn about it more

Answer 11

@SAN I get it now
So after we get the middle, this code now on going
for(let a = 0; a < arr.length/2+1; a++) {
if(arr[i-a]!=-arr[i+1+a]) {
Seq = arr.slice(i-a+1,i+a+1);
break

why must arr.length/2+1?

and the if is the checker if the one we check is not balanced like the other we remove the number, right?

Answer 12

Jansen Su
I'm still unclear whether you want to find the longest balanced sub sequence

1, 2, -2, -1 // longest balanced sub sequence

Or make the entire array balanced

1, 2, -2, -1, -2, 2, 1 // modify last 3

Answer 13

@SAN if the case for this one
console.log(BalanceSeq([2,3,2,-8,1,3,-3,-1,8,-2,-3,4,1]))
so I want the case to be like balanced sub sequence must be positive first then negative close

so for that result should be 1,3,-3,-1

from your code how to change that to be only open positive and closing negative?

Answer 14

Привет всем