50 lines
855 B
Go
50 lines
855 B
Go
// Package q43 implements a solution for https://leetcode.com/problems/multiply-strings/
|
|
package q43
|
|
|
|
import "slices"
|
|
|
|
func multiply(num1, num2 string) string {
|
|
if num1 == "0" || num2 == "0" {
|
|
return "0"
|
|
}
|
|
|
|
l1, l2 := len(num1), len(num2)
|
|
res := make([]byte, l1+l2)
|
|
|
|
// Calculation
|
|
for i1 := range l1 {
|
|
n1 := num1[l1-1-i1] - '0'
|
|
if n1 == 0 {
|
|
continue
|
|
}
|
|
for i2 := range l2 {
|
|
n2 := num2[l2-1-i2] - '0'
|
|
j := i1 + i2
|
|
res[j] += n1 * n2
|
|
if res[j] > 9 {
|
|
res[j+1] += res[j] / 10
|
|
res[j] = res[j] % 10
|
|
}
|
|
}
|
|
for i := l2 + i1; res[i] > 9; i++ {
|
|
res[i+1] += res[i] / 10
|
|
res[i] = res[i] % 10
|
|
}
|
|
}
|
|
|
|
// Post process
|
|
for i := len(res) - 1; i >= 0; i-- {
|
|
if res[i] > 0 {
|
|
res = res[:i+1]
|
|
break
|
|
}
|
|
}
|
|
|
|
slices.Reverse(res)
|
|
for i := range res {
|
|
res[i] = res[i] + '0'
|
|
}
|
|
return string(res)
|
|
}
|
|
|
|
var _ = multiply
|