UVA 11995 I Can Guess the Data Structure!

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.

2

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

61 11 21 32 12 22 361 11 21 32 32 22 121 12 241 21 12 12 271 21 51 11 32 51 42 4

Output for the Sample Input

queuenot sureimpossiblestackpriority 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;    elsefuck[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;}