989

2 files changed, 70 insertions, 0 deletions

diff --git a/989/go.mod b/989/go.mod
new file mode 100644
index 0000000..92068a8
--- /dev/null
+++ b/989/go.mod
@@ -0,0 +1,3 @@
+module 989
+
+go 1.19
diff --git a/989/main.go b/989/main.go
new file mode 100644
index 0000000..3bbc590
--- /dev/null
+++ b/989/main.go
@@ -0,0 +1,67 @@
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+func getNthDigit(num, k int) int {
+	result := num
+	if k-1 > 0 {
+		result -= num - (num/int(math.Pow10(k-1)))*int(math.Pow10(k-1))
+	}
+
+	if math.Pow10(k) <= float64(num) {
+		result -= (num / int(math.Pow10(k))) * int(math.Pow10(k))
+	}
+	// result := num - (num/int(math.Pow10(k)))*int(math.Pow10(k)) - (num/int(math.Pow10(k-2)))*int(math.Pow10(k-2))
+
+	result /= int(math.Pow10(k - 1))
+	// fmt.Println(num, k, result)
+	return result
+}
+
+func addToArrayForm(num []int, k int) []int {
+	length := int(math.Max(float64(len(num))+1., 5.))
+	result := make([]int, length)
+	carry := false
+	num_index := len(num) - 1
+
+	var sum int
+
+	for i := length - 1; i >= 0; i-- {
+		if num_index >= 0 {
+			sum = num[num_index] + getNthDigit(k, (length-i))
+		} else {
+			sum = getNthDigit(k, (length - i))
+		}
+		if carry {
+			sum++
+		}
+		if sum >= 10 {
+			carry = true
+		} else {
+			carry = false
+		}
+		result[i] = sum % 10
+		num_index--
+	}
+
+	if carry {
+		result[0] = 1
+	}
+
+	for j := 0; j < length; j++ {
+		if result[j] != 0 {
+			return result[j:]
+		}
+	}
+	return result
+}
+
+func main() {
+	fmt.Println(addToArrayForm([]int{1, 2, 0, 0}, 34))
+	fmt.Println(addToArrayForm([]int{2, 7, 4}, 181))
+	fmt.Println(addToArrayForm([]int{2, 1, 5}, 806))
+	fmt.Println(addToArrayForm([]int{0}, 806))
+}