/**
* 989. Add to Array-Form of Integer
* https://leetcode.com/problems/add-to-array-form-of-integer/description/
* For a non-negative integer X, the array-form of X is an array of its digits in left to right order.
* For example, if X = 1231, then the array form is [1,2,3,1].
Given the array-form A of a non-negative integer X, return the array-form of the integer X+K.
Example 1:
Input: A = [1,2,0,0], K = 34
Output: [1,2,3,4]
Explanation: 1200 + 34 = 1234
Example 2:
Input: A = [2,7,4], K = 181
Output: [4,5,5]
Explanation: 274 + 181 = 455
Example 3:
Input: A = [2,1,5], K = 806
Output: [1,0,2,1]
Explanation: 215 + 806 = 1021
* */
class Solution {
fun addToArrayForm(A: IntArray, K: Int): List<Int> {
val result = ArrayList<Int>()
val kStr = K.toString()
var i = A.size - 1
var j = kStr.length - 1
var carry = 0
while (i >= 0 || j >= 0) {
var temp = 0
if (i >= 0) {
temp += A[i]
}
if (j >= 0) {
temp += (kStr[j].toInt() - '0'.toInt())
}
temp += carry
if (temp >= 10) {
/*
也学习下英文：
* 个位 ones place
* 个位数 ones digit
* 十位 tens place
* 十位数 tens digit
* 百位 hundreds place
* 百位数 hundreds digit
* 千位 thousands place
* 千位数 thousands digit
* */
carry = temp / 10//get carry, if temp is 15 then carry is 1
temp = temp % 10//get ones digit, if temp is 15 then ones digit is 5
} else {
carry = 0
}
result.add(0, temp)
i--
j--
}
if (carry != 0){
result.add(0, carry)
}
return result
}
}
