/**
* use the recursion to add the big integer.
*
* @param num1
* @param num2
* @param isCarry
* @param result
*/
public static void addBigInt(StringBuffer num1, StringBuffer num2, int pos,
boolean isCarry, StringBuffer result) {
if (pos < num1.length() || pos < num2.length()) {
int value = 0;
if (isCarry) {
value++;
}
char temp1 = pos < num1.length() ? num1.charAt(pos) : '0';
char temp2 = pos = 10) {
isCarry = true;
value -= 10;
} else {
isCarry = false;
}
result.append(value);
addBigInt(num1, num2, ++pos, isCarry, result);
} else {
if (isCarry) {
result.append(’1′);
addBigInt(num1, num2, ++pos, false, result);
}
}

}

/**
* add method for big number.
*
* @param num1
* @param num2
*/
public static String addBigInt(StringBuffer num1, StringBuffer num2) {
StringBuffer result = new StringBuffer();

num1.reverse();
num2.reverse();

addBigInt(num1, num2, 0, false, result);

result.reverse();

return result.toString();
}
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