题解

#include<bits/stdc++.h>
using namespace std;

string s1, s2;		
deque<char>q1, q2, q3;
bool flag = true; 							
bool flag1 = true;							
 
void Input_deque() {
	int len1 = s1.length(), len2 = s2.length();
	for(int i = 0; i < len1; i++) q1.push_back(s1[i]);
	for(int i = 0; i < len2; i++) q2.push_back(s2[i]);
}

void Output_deque(deque<char>q) {
	int siz = q.size();
	while(!q.empty()) {
		cout << q.front();
		q.pop_front();
	}
}

int main() {
	ios::sync_with_stdio(false);
	cin>>s1>>s2;	
	Input_deque();
	while(1) {
		
		if(flag == true) {
			
			char a = q1.front();   	q1.pop_front();    
			q3.push_back(a);			
			if(count(q3.begin(), q3.end(), a) >= 2) {	
				q3.pop_back();    q1.push_back(a);	 
				while(1) {
					char c = q3.back();
					q3.pop_back();
					q1.push_back(c);
					if(c == a) break;
				}
				flag = true; continue;			
			} 
		}
		flag = false;
		
		if(q1.empty()) { flag1=false; break;}
		else if(q2.empty()) break;	
		 
		 
		if(flag == false) {
			char b = q2.front();    q2.pop_front();
			q3.push_back(b);
			if(count(q3.begin(), q3.end(), b) >= 2) {
				q3.pop_back();    q2.push_back(b);	 
				while(1) {
					char c = q3.back();
					q3.pop_back();
					q2.push_back(c);
					if(c == b) break;
				}
				flag = false; continue;					 
			}
		}
		flag = true; 
		if(q1.empty()) { flag1=false; break;}
		else if(q2.empty()) break;	
		
	}
	
	if(flag1 == false)
		Output_deque(q2);
	else Output_deque(q1);
return 0; }