题目描述
blablabla
样例
import java.util.*;
public class Main{
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
String a = sc.nextLine(), b = sc.nextLine();
if(b.length() > a.length() || (a.length() == b.length() && a.compareTo(b) < 0)){
System.out.println("-" + minus(b, a));
}else{
System.out.println(minus(a, b));
}
}
private static StringBuilder minus(String a, String b){
StringBuilder ans = new StringBuilder(Math.max(a.length(), b.length()));
for(int i = 0, x = 0; i < a.length() || i < b.length(); i++){
if(i < a.length()) x = a.charAt(a.length() - i - 1) - '0' - x;
if(i < b.length()) x -= b.charAt(b.length() - i - 1) - '0';
ans.append((x + 10) % 10);
x = x < 0 ? 1 : 0;
}
while(ans.length() > 1 && ans.charAt(ans.length() - 1) == '0') ans.deleteCharAt(ans.length() - 1);
return ans.reverse();
}
}