View Code of Problem 3689

#include <iostream>
#include <algorithm>
#include <string>
#include <stack>
#include <vector>
#include <set>
using namespace std;
stack<int> han(string a,string b ){
	stack<int> temp;
		int k=0,p=a.length()-1,q=b.length()-1;//p,q是a,b的下标，k为借位 
		for(;p>=0&&q>=0;p--,q--){
			if(a[p]-k>=b[q]){//a>=b
				int c=a[p]-b[q]-k;
				temp.push(c);
				k=0;
			}else{//a<b
				int c=a[p]-b[q]-k+10;
				temp.push(c);
				k=1;
			}
		}
		for(;p>=0;p--){//a不为0的时候 
			int c=a[p]-'0'-k;
			if(c<0){
				k=1;
				c+=10;
			}else k=0;
			temp.push(c);
		}
	return temp;		
}
int main() {
	int t;
	cin>>t;
	for(int i=1;i<=t;i++){
		string a,b;
		cin>>a;
		cin>>b;
		
		int flag=0;//正负 
		if(a.length()<b.length())
			flag=1;
		else if(a.length()==b.length())
			flag=a>=b?0:1;
			
		stack<int> temp;
		int count=0;
		cout<<"Case #"<<i<<":"<<endl;
		 
		if(flag){
			cout<<"-";
			temp=han(b,a);
		}
		else temp=han(a,b);
		
		while(!temp.empty()){
				int c=temp.top();
				if(c!=0){
					count=1;
					cout<<temp.top();
				}	
				else if(c==0&&count==1)
					cout<<temp.top();
				temp.pop();
		} 
		if(count==0)
			cout<<0;
		cout<<endl;
	}
        return 0;
}