UVA 11995 I Can Guess the Data Structure!

最新推荐文章于 2024-07-19 19:26:39 发布

原创最新推荐文章于 2024-07-19 19:26:39 发布 · 942 阅读

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本文介绍了一个有趣的问题：通过一系列操作及返回值来猜测底层所使用的是栈、队列还是优先队列等数据结构，并提供了一段C++代码实现来解决这个问题。

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I Can Guess the Data Structure!

There is a bag-like data structure, supporting two operations:

1 x

Throw an element x into the bag.

Take out an element from the bag.

Given a sequence of operations with return values, you're going to guess the data structure. It is a stack (Last-In, First-Out), a queue (First-In, First-Out), a priority-queue (Always take out larger elements first) or something else that you can hardly imagine!

Input

There are several test cases. Each test case begins with a line containing a single integer n (1<=n<=1000). Each of the next n lines is either a type-1 command, or an integer 2 followed by an integer x. That means after executing a type-2 command, we get an element xwithout error. The value of x is always a positive integer not larger than 100. The input is terminated by end-of-file (EOF). The size of input file does not exceed 1MB.

Output

For each test case, output one of the following:

stack

It's definitely a stack.

queue

It's definitely a queue.

priority queue

It's definitely a priority queue.

impossible

It can't be a stack, a queue or a priority queue.

not sure

It can be more than one of the three data structures mentioned above.

Sample Input

Output for the Sample Input

queue
not sure
impossible
stack
priority queue

题意：1为放入，2为取出，判断输入的数据判断该数据结构是栈，队列，还是优先队列。。

思路：直接模拟判断。

#include <stdio.h>
#include <string.h>

int n;
int sb[1005][2];
int fuck[1005];
int fuckk;
int sta()
{
    memset(fuck, 0, sizeof(fuck));
    fuckk  = 1;
    for (int i = 0; i < n; i ++)
    {
	if (sb[i][0] == 1)
	{
	    fuck[fuckk ++] = sb[i][1];
	}
	else if (sb[i][0] == 2)
	{
	    fuckk --;
	    if (fuck[fuckk] != sb[i][1])
		return 0;
	    else
		fuck[fuckk] = 0;
	}
    }
    return 1;
}

int que()
{
    memset(fuck, 0, sizeof(fuck));
    fuckk = 1;
    for (int i = 0; i < n ; i ++)
    {
	if (sb[i][0] == 1)
	    fuck[fuckk ++] = sb[i][1];
	else if (sb[i][0] == 2)
	{
	    if (fuck[1] != sb[i][1])
		return 0;
	    else
	    {
		for (int i = 1; i < fuckk; i ++)
		{
		    fuck[i] = fuck[i + 1];
		}
		fuckk --;
	    }
	}
    }
    return 1;
}

int findmax()
{
    int maxx = 0;
    int maxxv = 0;
    for (int i = 1; i < fuckk; i ++)
    {
	if (maxx < fuck[i])
	{
	    maxx = fuck[i];
	    maxxv = i;
	}
    }
    return maxxv;
}
int prq()
{
    memset(fuck, 0, sizeof(fuck));
    fuckk = 1;
    for (int i = 0; i < n ; i ++)
    {
	if (sb[i][0] == 1)
	    fuck[fuckk ++] = sb[i][1];
	else if (sb[i][0] == 2)
	{
	    int sbb = findmax();
	    if (fuck[sbb] != sb[i][1])
		return 0;
	    else
	    {
		for (int i = sbb; i < fuckk; i ++)
		{
		    fuck[i] = fuck[i + 1];
		}
		fuckk --;
	    }
	}
    }
    return 1;
}
int main()
{   
    while (scanf("%d", &n) != EOF)
    {
	memset(fuck, 0, sizeof(fuck));
	memset(sb, 0, sizeof(sb));
	for (int i = 0; i < n; i ++)
	{
	    scanf("%d%d", &sb[i][0], &sb[i][1]);
	}
	if (sta() && !que() && !prq())
	    printf("stack\n");
	else if (!sta() && que() && !prq())
	    printf("queue\n");
	else if (!sta() && !que() && prq())
	    printf("priority queue\n");
	else if (!sta() && !que() && !prq())
	    printf("impossible\n");
	else
	    printf("not sure\n");
    }
    return 0;
}