stack+DFS ZOJ 1004 Anagrams by Stack

题目传送门

 /*
     stack 容器的应用：    要求字典序升序输出，所以先搜索入栈的
         然后逐个判断是否满足答案，若不满足，回溯继续搜索，输出所有符合的结果
 */
 #include <cstdio>
 #include <iostream>
 #include <algorithm>
 #include <stack>
 #include <cmath>
 #include <cstring>
 #include <vector>
 using namespace std;

 const int MAXN = 1e4 + ;
 const int INF = 0x3f3f3f3f;

 string s1, s2;
 int len;
 stack<char> S;
 vector<char> V;

 void DFS(int push, int pop)
 {
     if (push == len && pop == len)
     {
         for (int i=; i<V.size (); ++i)
             cout << V[i] << " ";
         cout << endl;
     }

     if (push +  <= len)        //入栈
     {
         S.push (s1[push]);
         V.push_back ('i');
         DFS (push+, pop);
         S.pop ();
         V.pop_back ();
     }

     if (pop +  <= push && pop +  <= len && S.top () == s2[pop])        //出栈
     {
         char ch = S.top ();
         S.pop ();
         V.push_back ('o');
         DFS (push, pop+);
         S.push (ch);
         V.pop_back ();
     }
 }

 int main(void)        //ZOJ 1004 Anagrams by Stack
 {
     //freopen ("ZOJ_1004.in", "r", stdin);

     while (cin >> s1 >> s2)
     {
         V.clear ();
         while (!S.empty ())    S.pop ();

         len = s1.length ();

         cout << "[" << endl;
         DFS (, );
         cout << "]" << endl;
     }

     return ;
 }

 /*
 [
 i i i i o o o i o o
 i i i i o o o o i o
 i i o i o i o i o o
 i i o i o i o o i o
 ]
 [
 i o i i i o o i i o o o
 i o i i i o o o i o i o
 i o i o i o i i i o o o
 i o i o i o i o i o i o
 ]
 [
 ]
 [
 i i o i o i o o
 ]
 */