n个元素进栈，输出所有出栈序列-卡特兰数-递归

#include <iostream>
#include <stack>
#include <queue>
#include <algorithm>
#include <string.h>
#include <cstdio>
#include <stdlib.h>
#include <cctype>
#include <stack>
#include <queue>

using namespace std;

void printAllOutStackSeq( queue<int> inQueue, int n, stack<int> st, queue<int> out )
{
if( n <= 0 || ( inQueue.empty() && st.empty() && out.empty() ) )
{
return;
}

if( out.size() == n )
{
while( !out.empty() )
{
cout << out.front() << ' ';
out.pop();
}

cout << endl;
return;
}

stack<int> stCopy = st;  // 备份一下，否则储转
queue<int> outCopy = out;

if( !st.empty() ) // 出栈，将元素出栈，push到结果队列中
{
out.push( st.top() );
st.pop();
printAllOutStackSeq( inQueue, n, st, out );
}

if( !inQueue.empty() ) // 入栈，将输入队列出队，进行入栈
{
stCopy.push( inQueue.front() );
inQueue.pop();
printAllOutStackSeq( inQueue, n, stCopy, outCopy );
}

return;
}

int main()
{
int ret = 0;

int a[] = { 1, 2, 3, 4 };
queue<int> inQueue;

for( int i = 0; i < 4; i++ )
{
inQueue.push( a[i] );
}

int n;
stack<int> st;
queue<int> out;

printAllOutStackSeq( inQueue, 4, st, out );

return ret;
}

/*
n个元素入栈，出栈序列个数： C(2n,n)/(n+1)
./a.out
1 2 3 4
1 2 4 3
1 3 2 4
1 3 4 2
1 4 3 2
2 1 3 4
2 1 4 3
2 3 1 4
2 3 4 1
2 4 3 1
3 2 1 4
3 2 4 1
3 4 2 1
4 3 2 1

./a.out|wc -l
14

*/