rt，RE on #6-#12，错误码6，Aborted / IOT trap.

#include<bits/stdc++.h>
#define f(i,a,b) for(int i = a ; i<=b ; i++)
using namespace std;
stack<int> stk;
string s,ans;
int main(){
    cin>>s;
    f(i,0,s.size()-1){
        if(s[i] == '('){stk.push(i); ans[i] = ')';}
        if(s[i] == '['){stk.push(i); ans[i] = ']';}
        if(s[i] == ')'||s[i] == ']'){
        	if(stk.empty()||ans[stk.top()]!=s[i]){
            	if (s[i] == ')') ans[i] = '('; 
				else ans[i] = '[';
			}
			else{
				 ans[stk.top()] = ' ';
				if(!stk.empty()) stk.pop();
			}
			
		}  
    }
    f(i,0,s.size()-1){
        if(ans[i] == '('||ans[i] == '[') cout<<ans[i];
        cout<<s[i];
        if(ans[i] == ')'||ans[i] == ']') cout<<ans[i];
    }
    return 0;
}