1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 #include <stdlib.h>
 5 #include <bits/stdc++.h>
 6 using namespace std;
 7 
 8 int main()
 9 {
10     string str;
11 
12     stack<int> s;
13     vector<vector<int> > vec;
14     int flag=1;
15 
16     cin>>str;
17     for(int i=0;i<str.length();i++)
18     {
19         if(str[i]==‘(‘)
20         {
21             //下标入栈
22             s.push(i+1);
23         }
24         else if(str[i]==‘)‘)
25         {
26             if(s.empty())
27             {
28                 flag=0;
29                 break;
30             }
31             else
32             {
33                 int left=s.top();
34                 int right=i+1;
35                 s.pop();
36                 vector<int> v;
37                 v.push_back(left);
38                 v.push_back(right);
39                 vec.push_back(v);
40             }
41         }
42     }
43     if(flag&&s.empty())
44     {
45         cout<<"Yes"<<endl;
46         for(int i=0;i<vec.size();i++)
47         {
48             cout<<vec[i][0]<<" "<<vec[i][1]<<endl;
49         }
50     }
51     else
52     {
53         cout<<"No"<<endl;
54     }
55     return 0;
56 }

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 #include <stdlib.h>
 5 #include <bits/stdc++.h>
 6 using namespace std;
 7 
 8 int main()
 9 {
10     //提高输入输出的速度
11     ios::sync_with_stdio(false);
12 
13     vector<string> vec;
14     int n;
15     cin>>n;
16 
17     string do_what;
18     string url;
19     int cursor=0;
20     for(int i=0;i<n;i++)
21     {
22         cin>>do_what;
23         if(do_what=="VISIT")
24         {
25             while(!vec.empty()&&cursor<vec.size()-1)
26             {
27                 vec.pop_back();
28             }
29             cin>>url;
30             vec.push_back(url);
31             cout<<url<<endl;
32             cursor=vec.size()-1;
33             continue;
34         }
35         else if(do_what=="BACK")
36         {
37             cursor--;
38             if(!vec.empty()&&0<=cursor&&cursor<vec.size())
39             {
40                 cout<<vec[cursor]<<endl;
41             }
42             else
43             {
44                 cout<<"Ignore"<<endl;
45                 if(cursor<0)
46                 {
47                     cursor=0;
48                 }
49             }
50         }
51         else if(do_what=="FORWARD")
52         {
53             cursor++;
54             if(!vec.empty()&&0<=cursor&&cursor<vec.size())
55             {
56                 cout<<vec[cursor]<<endl;
57             }
58             else
59             {
60                 cout<<"Ignore"<<endl;
61                 if(cursor==vec.size())
62                 {
63                     cursor=vec.size()-1;
64                 }
65             }
66         }
67     }
68     return 0;
69 }