uva-11995 - I Can Guess the Data Structure!(栈,优先队列,队列,水题)
11995 - 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 x without error. The value of x
is always a positive integer not larger than 100. The input is terminated by end-of-file (EOF).
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
6
1 1
1 2
1 3
2 1
2 2
2 3
6
1 1
1 2
1 3
2 3
2 2
2 1
2
1 1
2 2
4
1 2
1 1
2 1
2 2
7
1 2
1 5
1 1
1 3
2 5
1 4
2 4
Sample Output
queue
not sure
impossible
stack
priority queue
题意:水。。。
代码:
#include<iostream> #include<cstdio> #include<cstring> #include<cmath> #include<algorithm> #include<queue> #include<vector> #include<stack> using namespace std; const int INF=0x3f3f3f3f; #define mem(x,y) memset(x,y,sizeof(x)) #define SI(x) scanf("%d",&x) #define SL(x) scanf("%lld",&x) #define PI(x) printf("%d",x) #define PL(x) printf("%lld",x) #define P_ printf(" ") #define T_T while(T--) #define F(i,s,x) for(i=s;i<x;i++) const double PI=acos(-1.0); typedef long long LL; int main(){ int n; while(~SI(n)){ int x,t; queue<int>q; priority_queue<int>sq; stack<int>S; int a=1,b=1,c=1; int temp=0; while(n--){ SI(t);SI(x); if(temp)continue; if(t==1){ q.push(x); sq.push(x); S.push(x); } else{ if(q.empty())temp=1; if(temp)continue; if(q.front()!=x)a=0; if(sq.top()!=x)b=0; if(S.top()!=x)c=0; q.pop(); sq.pop(); S.pop(); } } if(temp||(a+b+c==0))puts("impossible"); else if(a+b+c>1)puts("not sure"); else if(a)puts("queue"); else if(b)puts("priority queue"); else if(c)puts("stack"); } return 0; }