package interview;
import java.nio.CharBuffer;
public class BigNumberAdd {
public static void main(String[] args) {
String value1 = "155";
String value2 = "555";
String result = add(value1, value2);
String result2 = add2(value1, value2);
System.out.println("the scan result is " + result);
System.out.println("the scan result2 is " + result2);
}
public static String add2(String strNumber1, String strNumber2) {
int str1length = strNumber1.length();
int str2Length = strNumber2.length();
int max = Math.max(str1length, str2Length);
char result[] = new char[max + 1];
for (int i = 0; i < max; ++i) {
int lastIndex1 = str1length - 1 - i;
int lastIndex2 = str2Length - 1 - i;
int resultIndex = result.length - 1 - i;
int value;
if (result[resultIndex] == 0) {
value = 0;
} else {
value = result[resultIndex] - '0';
}
if (strNumber1.charAt(lastIndex1) >= '0' && strNumber1.charAt(lastIndex1) <= '9') {
if (lastIndex1 >= 0) {
value += strNumber1.charAt(lastIndex1) - '0';
}
} else {
throw new RuntimeException("error");
}
if (strNumber2.charAt(lastIndex1) >= '0' && strNumber1.charAt(lastIndex1) <= '9') {
if (lastIndex2 >= 0) {
value += strNumber2.charAt(lastIndex2) - '0';
}
} else {
throw new RuntimeException("error");
}
int overFlow = value / 10;
value = value % 10;
result[resultIndex] = (char) ((char) value + (char) '0');
result[resultIndex - 1] = (char) ((char) overFlow + (char) '0');
}
if (result[0] == '0') {
return new String(result, 1, result.length - 1);
} else {
return new String(result);
}
}
public static String add(String strNumber1, String strNumber2) {
int max = Math.max(strNumber1.length(), strNumber2.length());
int overFlowValue = 0;
char result[] = new char[max + 1];
for (int i = 0; i < max; ++i) {
int str1length = strNumber1.length();
int str2Length = strNumber2.length();
int index1 = i - (max - str1length);
int index2 = i - (max - str2Length);
int intValue1 = 0;
int intValue2 = 0;
if (index1 >= 0) {
intValue1 = strNumber1.charAt(index1) - '0';
}
if (index2 >= 0) {
intValue2 = strNumber2.charAt(index2) - '0';
}
int overFlow = intValue1 + intValue2;
for (int j = i; j >= 0; --j) {
if (overFlow == 0) {
break;
}
if (result[j + 1] == 0) {
result[j + 1] = '0';
}
int preValue = result[j + 1] - '0';
preValue = preValue + overFlow;
overFlow = preValue / 10;
preValue = preValue % 10;
result[j + 1] = (char) ((char) preValue + '0');
}
if (overFlow != 0) {
overFlowValue = overFlowValue + overFlow;
}
}
if (overFlowValue != 0) {
result[0] = (char) ((char) overFlowValue + '0');
return String.valueOf(result, 0, result.length);
} else {
return String.valueOf(result, 1, result.length - 1);
}
}
}
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