题目链接：http://poj.org/problem?id=1028
解题思路：STL —— stack
1 /////////////////////////////////////////////////////////////////////////// 2 //problem_id: poj 1028 3 //user_id: SCNU20102200088 4 /////////////////////////////////////////////////////////////////////////// 5 6 #include <algorithm> 7 #include <iostream> 8 #include <iterator> 9 #include <iomanip> 10 #include <cstring> 11 #include <cstdlib> 12 #include <string> 13 #include <vector> 14 #include <cstdio> 15 #include <cctype> 16 #include <cmath> 17 #include <queue> 18 #include <stack> 19 #include <list> 20 #include <set> 21 #include <map> 22 using namespace std; 23 24 /////////////////////////////////////////////////////////////////////////// 25 typedef long long LL; 26 const double PI=acos(-1.0); 27 /////////////////////////////////////////////////////////////////////////// 28 29 /////////////////////////////////////////////////////////////////////////// 30 //Add Code: 31 /////////////////////////////////////////////////////////////////////////// 32 33 int main(){ 34 /////////////////////////////////////////////////////////////////////// 35 //Add code: 36 string s,current; 37 stack<string> forward,backward; 38 current="http://www.acm.org/"; 39 while(cin>>s){ 40 if(s[0]=='B'){ 41 if(!backward.empty()){ 42 forward.push(current); 43 current=backward.top(); 44 backward.pop(); 45 cout<<current<<endl; 46 } 47 else cout<<"Ignored"<<endl; 48 } 49 else if(s[0]=='F'){ 50 if(!forward.empty()){ 51 backward.push(current); 52 current=forward.top(); 53 forward.pop(); 54 cout<<current<<endl; 55 } 56 else cout<<"Ignored"<<endl; 57 } 58 else if(s[0]=='V'){ 59 backward.push(current); 60 cin>>current; 61 cout<<current<<endl; 62 while(!forward.empty()) forward.pop(); 63 } 64 else if(s[0]=='Q') break; 65 } 66 /////////////////////////////////////////////////////////////////////// 67 return 0; 68 } 69 70 /////////////////////////////////////////////////////////////////////////// 71 /* 72 Testcase: 73 Input: 74 VISIT http://acm.ashland.edu/ 75 VISIT http://acm.baylor.edu/acmicpc/ 76 BACK 77 BACK 78 BACK 79 FORWARD 80 VISIT http://www.ibm.com/ 81 BACK 82 BACK 83 FORWARD 84 FORWARD 85 FORWARD 86 QUIT 87 Output: 88 http://acm.ashland.edu/ 89 http://acm.baylor.edu/acmicpc/ 90 http://acm.ashland.edu/ 91 http://www.acm.org/ 92 Ignored 93 http://acm.ashland.edu/ 94 http://www.ibm.com/ 95 http://acm.ashland.edu/ 96 http://www.acm.org/ 97 http://acm.ashland.edu/ 98 http://www.ibm.com/ 99 Ignored 100 */ 101 ///////////////////////////////////////////////////////////////////////////