#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
using namespace std;

#define maxn 250

struct Edge
{
	int v, next;
} edge[maxn * maxn];

int n;
int stock[maxn], f[maxn];
int head[maxn], ecount, color[maxn], q[maxn];
int out[maxn];
bool ok;
int stk1[maxn], stk2[maxn];
int top1, top2, step;

void input()
{
	for (int i = 0; i < n; i++)
	{
		scanf("%d", &stock[i]);
		out[i] = stock[i];
	}
}

void addedge(int &a, int &b)
{
	edge[ecount].next = head[a];
	edge[ecount].v = b;
	head[a] = ecount++;
}

void bfs(int &s)
{
	int front = 0;
	int rear = 1;
	q[0] = s;
	color[s] = 1;
	while (front != rear)
	{
		int a = q[front++];
		for (int i = head[a]; i != -1; i = edge[i].next)
		{
			int b = edge[i].v;
			if (!color[b])
			{
				q[rear++] = b;
				color[b] = 3 - color[a];
			}
			else if (color[a] == color[b])
			{
				ok = false;
				return;
			}
		}
	}
}

void make(int i)
{
	int a = stock[i];
	bool did = true;
	while (did)
	{
		did = false;
		if (top1 > 0 && stk1[top1 - 1] == out[step])
		{
			top1--;
			printf("pop 1\n");
			step++;
			did = true;
		}
		if (top2 > 0 && stk2[top2 - 1] == out[step])
		{
			top2--;
			printf("pop 2\n");
			step++;
			did = true;
		}
	}
	if (i < 0)
		return;
	if (color[i] == 1)
	{
		stk1[top1++] = a;
		printf("push 1\n");
	}
	else
	{
		stk2[top2++] = a;
		printf("push 2\n");
	}
}

void print()
{
	top1 = top2 = 0;
	step = 0;
	for (int i = n - 1; i >= 0; i--)
		make(i);
	make(-1);
}

void work()
{
	memset(head, -1, sizeof(head));
	f[0] = stock[0];
	for (int i = 1; i < n; i++)
		f[i] = min(f[i - 1], stock[i]);
	ecount = 0;
	for (int i = 1; i < n - 1; i++)
	{
		for (int j = i + 1; j < n; j++)
		{
			if (stock[j] >= stock[i])
				continue;
			if (stock[j] > f[i - 1])
			{
				addedge(i, j);
				addedge(j, i);
			}
		}
	}
	ok = true;
	memset(color, 0, sizeof(color));
	for (int i = 0; i < n; i++)
	{
		if (!color[i])
			bfs(i);
		if (!ok)
		{
			printf("impossible\n");
			return;
		}
	}
	print();
}

int main()
{
	//freopen("t.txt", "r", stdin);
	int t = 0;
	while (scanf("%d", &n), n)
	{
		t++;
		printf("#%d\n", t);
		input();
		sort(out, out + n);
		work();
	}
	return 0;
}

• 嗯，很好！ (0) fanhqme 2011-08-02 18:21:17