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