public class Solution

{

public String multiply(String num1, String num2)

{

int len1 = num1.length();

int len2 = num2.length();

int[] dp = new int[len1 + len2];

for (int i = len1 - 1; i >= 0; i--)

{

for (int j = len2 - 1; j >= 0; j--)

{

dp[len1 + len2 - i - j - 2] += Character.getNumericValue(num1.charAt(i)) * Character.getNumericValue(num2.charAt(j));

dp[len1 + len2 - i - j - 1] += dp[len1 + len2 - i - j - 2] / 10;

dp[len1 + len2 - i - j - 2] %= 10;

}

}

StringBuilder ret = new StringBuilder();

boolean start = false;

for (int i = dp.length - 1; i >= 0; i--)

{

if (dp[i] != 0)

{

start = true;

}

if (start)

{

ret.append(dp[i]);

}

}

if (!start)

return "0";

return ret.toString();

}

}