multiply-strings

multiply-strings/sol.go

@@ -0,0 +1,36 @@
+package main
+
+// idk complexity
+func multiply(num1 string, num2 string) string {
+	l1, l2 := len(num1), len(num2)
+	to_sum := make(map[int]int)
+	max_p10 := 0
+	for p1 := l1 - 1; p1 >= 0; p1-- {
+		for p2 := l2 - 1; p2 >= 0; p2-- {
+			n1, n2 := int(num1[p1])-48, int(num2[p2])-48
+			p10 := l1 - 1 - p1 + l2 - 1 - p2
+			d := n1 * n2
+			if p10 > max_p10 {
+				max_p10 = p10
+			}
+			to_sum[p10] = to_sum[p10] + d
+		}
+	}
+	sum := ""
+	for p := 0; p <= max_p10; p++ {
+		d := to_sum[p]
+		sum = string(48+(d%10)) + sum
+		to_sum[p+1] = to_sum[p+1] + d/10
+		if p+1 > max_p10 && d/10 > 0 {
+			max_p10 = p + 1
+		}
+	}
+	for len(sum) > 1 && sum[0] == '0' {
+		sum = sum[1:]
+	}
+	return sum
+}
+
+func main() {
+	println(multiply("123456", "0"))
+}