标签：
Given two numbers represented as strings, return multiplication of the numbers as a string.
Note: The numbers can be arbitrarily large and are non-negative.
这道题的意思是字符串表示的数字相乘。
没啥好说的直接付代码。
public String multiply(String num1, String num2) {
BigInteger temp1 = new BigInteger(num1);
BigInteger temp2 = new BigInteger(num2);
BigInteger result = temp1.multiply(temp2);
return result.toString();
}
另外一种是实现：
public String multiply1(String num1, String num2) {
if (num1 == null || num2 == null) {
return null;
}
int len1 = num1.length(), len2 = num2.length();
int len3 = len1 + len2;
int i, j, product, carry;
int[] num3 = new int[len3];
for (i = len1 - 1; i >= 0; i--) {
carry = 0;
for (j = len2 - 1; j >= 0; j--) {
product = carry + num3[i + j + 1] +
Character.getNumericValue(num1.charAt(i)) *
Character.getNumericValue(num2.charAt(j));
num3[i + j + 1] = product % 10;
carry = product / 10;
}
num3[i + j + 1] = carry;
}
StringBuilder sb = new StringBuilder();
i = 0;
while (i < len3 - 1 && num3[i] == 0) {
i++;
}
while (i < len3) {
sb.append(num3[i++]);
}
return sb.toString();
}
标签：
原文地址：http://www.cnblogs.com/gracyandjohn/p/4504538.html
