plus-one
You are given a large integer represented as an integer array digits, where each digits[i] is the ith digit of the integer. The digits are ordered from most significant to least significant in left-to-right order. The large integer does not contain any leading 0's.
Increment the large integer by one and return the resulting array of digits.
Example 1
Input: digits = [1,2,3]
Output: [1,2,4]
Explanation: The array represents the integer 123.
Incrementing by one gives 123 + 1 = 124.
Thus, the result should be [1,2,4].
Example 2
Input: digits = [4,3,2,1]
Output: [4,3,2,2]
Explanation: The array represents the integer 4321.
Incrementing by one gives 4321 + 1 = 4322.
Thus, the result should be [4,3,2,2].
Example 3
Input: digits = [9]
Output: [1,0]
Explanation: The array represents the integer 9.
Incrementing by one gives 9 + 1 = 10.
Thus, the result should be [1,0].
Solution
plus-one
/**
* @param {number[]} digits
* @return {number[]}
*/
var plusOne = function (digits) {
// starting from the last element
// and going backwards to the first element
for (let i = digits.length - 1; i >= 0; i--) {
if (digits[i] < 9) {
digits[i]++;
break;
} else if (digits[i] === 9 && i !== 0) {
digits[i] = 0;
}
// we need to take care another edge case
// is that if the first element is 9 then
// we need to let it be [1,0] as well
else if (digits[i] === 9 && i === 0) {
digits[i] = 0;
digits.unshift(1);
}
}
return digits;
};