Question

How to convert an array of digits to an integer add 1 and convert it back to an array of digits in Node.js

Answer 1

function convertArrayOfDigitsToIntNumber(arr) {
    let n = 0;
   
    for (let digit of arr) {
        n = n * 10 + digit;
    }
   
    return n;
}
 
function convertIntNumberToArrayOfDigits(digits, n) {
    let i = digits.length - 1;
   
    while (n > 0) {
        digits[i] = n % 10;
        n = Math.floor(n / 10);
        i--;
    }
}
 
let arr = [9, 4, 8, 9];
 
let n = convertArrayOfDigitsToIntNumber(arr);
 
n++;
 
convertIntNumberToArrayOfDigits(arr, n);
 
console.log("n = " + n);
console.log(arr.toString());
 
 
  
   
/*
run:
      
n = 9490
9,4,9,0
      
*/

 

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Answer 2

function addOne(arr) {
    for (let i = 0; i < arr.length; i++) {
        if (arr[i] > 9 || arr[i] < -1) return null;
    }
    
    let num = parseInt(arr.join('')) + 1;
    arr = num.toString().split('').map(Number);
    
    return arr;
}


let arr = [9, 4, 8, 9];

arr = addOne(arr);

console.log(arr);


 
  
/*
run:
     
[ 9, 4, 9, 0 ]
     
*/

 

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