Determining beautiful number string in JavaScript

A numeric string, str, is called a beautiful string if it can be split into a sequence arr of two or more positive integers, satisfying the following conditions −

• arr[i] - arr[i - 1] = 1, for any i in the index of sequence, i.e., each element in the sequence is more than the previous element.

• No element of the sequence should contain a leading zero. For example, we can split '50607' into the sequence [5, 06, 07], but it is not beautiful because 06 and 07 have leading zeros.

• The contents of the sequence cannot be rearranged.

For example −

If the input string is −

const str = '91011';

Then the output should be −

const output = true;

because the desired sequence is [9, 10, 11];

Example

The code for this will be −

const str = '91011'; const isBeautiful = (str) => {    let i = 1;    let count=0;    const { length } = str;    while(i <= length / 2){       let check = true;       let j = i;       let left = BigInt(str.substring(0,j));       let nextRange = (left + 1n).toString().length;       while(j + nextRange <= length){          let right=BigInt(str.substring(j,j+nextRange));          if(left === right-1n){             left=right;             j+=nextRange;             nextRange=(left+1n).toString().length;             count=j;          }else{             check=false;             break;          }       };       if(check === true && count === length){          return true;       }       i++;    };    return false; }; console.log(isBeautiful(str));

Output

And the output in the console will be −

true