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MultiplyStrings.java
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MultiplyStrings.java
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public class Solution {
public String multiply(String num1, String num2) {
num1 = new StringBuilder(num1).reverse().toString();
num2 = new StringBuilder(num2).reverse().toString();
int[] sums = new int[num1.length() + num2.length()];
for (int i = 0; i < num1.length(); i++) {
for (int j = 0; j < num2.length(); j++) {
sums[i+j] += ((int)num1.charAt(i)-(int)'0') * ((int)num2.charAt(j)-(int)'0');
}
}
StringBuilder sb = new StringBuilder();
int carry = 0;
for (int i = 0; i < sums.length; i++) {
int sum = sums[i] + carry;
int digit = sum % 10;
carry = sum / 10;
sb.append(digit);
}
sb = sb.reverse();
while (sb.charAt(0) == '0' && sb.length() > 1) {
sb.deleteCharAt(0);
}
return sb.toString();
}
}