LeetCode 43. 字符串相乘

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题目描述
思路分析
参考代码

题目描述

🔥 43. 字符串相乘

思路分析

竖式乘法

参考代码

func multiply(num1 string, num2 string) string {
	if num1 == "0" || num2 == "0" {
		return "0"
	}
	m, n := len(num1), len(num2)
	res := make([]int, m+n)
	for i := m - 1; i >= 0; i-- {
		for j := n - 1; j >= 0; j-- {
			mul := int(num1[i]-'0') * int(num2[j]-'0')
			sum := mul + res[i+j+1]
			res[i+j+1] = sum % 10
			res[i+j] += sum / 10
		}
	}
	var sb strings.Builder
	for _, digit := range res {
		sb.WriteString(fmt.Sprintf("%d", digit))
	}
	return strings.TrimLeft(sb.String(), "0")
}