A number is gapful if it is at least 3 digits long and is divisible by the number formed by stringing the first and last numbers together. The smallest number that fits this description is 100. First digit is 1, last digit is 0, forming 10, which is a factor of 100. Therefore, 100 is gapful.
We are required to create a function that takes a number n and returns the closest gapful number (including itself). If there are 2 gapful numbers that are equidistant to n, return the lower one.
Some examples −
gapful(25) ➞ 100 gapful(100) ➞ 100 gapful(103) ➞ 105
Example
Following is the code −
const num = 4780;
const isGapful = n => {
if (n < 100){
return false;
}
const temp = Array.from(n.toString());
return n % (temp[0] + temp[temp.length - 1]) === 0;
}
function getClosestGapful(n) {
let left = n, right = n;
while (!isGapful(right)){
right++;
}
if (n < 100){
return right;
}
while (!isGapful(left)){
left++;
}
return n - left <= right - n ? left : right;
};
console.log(getClosestGapful(25));
console.log(getClosestGapful(num));Output
This will produce the following output on console −
100 4800