nyist1128手速(双端队列deque的用法)

题目链接：http://acm.nyist.net/JudgeOnline/problem.php?pid=1128题目解析；双端队列的用法,可以在队列的头和尾进行操作,从头和尾插入是push_front()和push_back()，从头和尾删是pop_front()和pop_back().代码如下：

01.

#include<cstdio>

02.

#include<cstring>

03.

#include<deque>

04.

using

namespace

std;

05.

int

main()

06.

{

07.

int

icase;

08.

deque<

int

>q;

09.

scanf

(

"%d"

,&icase);

10.

while

(icase--)

11.

{

12.

q.clear();

13.

int

n;

14.

scanf

(

"%d"

,&n);

15.

int

a,b;

16.

int

s=0;

17.

while

(n--)

18.

{

19.

scanf

(

"%d"

,&a);

20.

if

(a==0)

21.

{

22.

scanf

(

"%d"

,&b);

23.

if

(s%2==0)

24.

q.push_front(b);

25.

else

26.

q.push_back(b);

27.

}

28.

if

(a==1)

29.

{

30.

scanf

(

"%d"

,&b);

31.

if

(s%2==0)

32.

q.push_back(b);

33.

else

34.

q.push_front(b);

35.

}

36.

if

(a==2)

37.

{

38.

if

(!q.empty())

39.

{

40.

if

(s%2==0)

41.

q.pop_front();

42.

else

43.

q.pop_back();

44.

}

45.

46.

}

47.

if

(a==3)

48.

{

49.

if

(!q.empty())

50.

{

51.

if

(s%2==0)

52.

q.pop_back();

53.

else

54.

q.pop_front();

55.

}

56.

57.

}

58.

if

(a==4)
s++;

59.

}

60.

if

(q.empty())

61.

printf

(

"-1\n"

);

62.

else

63.

{

64.

int

p=q.size();

65.

for

(

int

i=0;i<p-1;i++)

66.

printf

(

"%d
"

,q[i]);

67.

printf

(

"%d\n"

,q[p-1]);

68.

}

69.

}

70.

return

0;

71.

}