import java.util.Arrays;

/**

* 43. 字符串相乘

*/

public class Multiply {

public String multiply(String num1, String num2){

if(num1.length()==0 || num2.length()==0 || num1.equals("0") || num2.equals("0")){

return "0";

}

int[] res = new int[num1.length()+num2.length()];

int temp=0;

for(int i=num1.length()-1; i>=0; i--){

int n1 = num1.charAt(i)-'0';

for(int j=num2.length()-1; j>=0; j--){

int n2 = num2.charAt(j) - '0';

temp = n1*n2+res[i+j+1];

res[i+j+1] = temp%10;

res[i+j] += temp/10;

}

}

StringBuilder sb = new StringBuilder();

for(int i=0; i<res.length; i++){

if(i==0 && res[i]==0){

continue;

}

sb.append(res[i]);

}

return sb.toString();

}

}