问题描述
给定两个字符串数字（长度小于110），要求计算两个字符串数字相乘的结果。题目链接：**点我**
样例输入输出
输入：num1 = “123” num2 = “456”
输出：”56088”
输入：num1 = “9999999999” num2 = “9999999999”
输出：”99999999980000000001”
问题解法
大数相乘的做法，直接模拟两个数字相乘即可。代码如下
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| class Solution
{
public String multiply(String num1, String num2)
{
int[] sums = new int[num1.length() + num2.length()];
for (int i = num1.length() - 1; i >= 0; i--)
{
for (int j = num2.length() - 1; j >= 0; j--)
{
int product = (num1.charAt(i) - '0') * (num2.charAt(j) - '0');
int temp = sums[i + j + 1] + product;
sums[i + j + 1] = temp % 10;
sums[i + j] = sums[i + j] + temp / 10;
}
}
boolean isStart = false;
StringBuilder result = new StringBuilder();
for (int i = 0; i < sums.length; i++)
{
if (sums[i] == 0 && !isStart)
{
continue;
}
isStart = true;
result.append(sums[i]);
}
if (result.length() == 0)
{
return "0";
}
else
{
return result.toString();
}
}
}
|