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