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  • Codeforces Round #366 (Div. 2) C. Thor (模拟)

    C. Thor

    time limit per test
    2 seconds
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    Thor is getting used to the Earth. As a gift Loki gave him a smartphone. There are n applications on this phone. Thor is fascinated by this phone. He has only one minor issue: he can't count the number of unread notifications generated by those applications (maybe Loki put a curse on it so he can't).

    q events are about to happen (in chronological order). They are of three types:

    1. Application x generates a notification (this new notification is unread).
    2. Thor reads all notifications generated so far by application x (he may re-read some notifications).
    3. Thor reads the first t notifications generated by phone applications (notifications generated in first t events of the first type). It's guaranteed that there were at least t events of the first type before this event. Please note that he doesn't read first t unread notifications, he just reads the very first t notifications generated on his phone and he may re-read some of them in this operation.

    Please help Thor and tell him the number of unread notifications after each event. You may assume that initially there are no notifications in the phone.

    Input

    The first line of input contains two integers n and q (1 ≤ n, q ≤ 300 000) — the number of applications and the number of events to happen.

    The next q lines contain the events. The i-th of these lines starts with an integer typei — type of the i-th event. Iftypei = 1 or typei = 2 then it is followed by an integer xi. Otherwise it is followed by an integer ti(1 ≤ typei ≤ 3, 1 ≤ xi ≤ n, 1 ≤ ti ≤ q).

    Output

    Print the number of unread notifications after each event.

    Examples
    input
    3 4
    1 3
    1 1
    1 2
    2 3
    output
    1
    2
    3
    2
    input
    4 6
    1 2
    1 4
    1 2
    3 3
    1 3
    1 3
    output
    1
    2
    3
    0
    1
    2
    Note

    In the first sample:

    1. Application 3 generates a notification (there is 1 unread notification).
    2. Application 1 generates a notification (there are 2 unread notifications).
    3. Application 2 generates a notification (there are 3 unread notifications).
    4. Thor reads the notification generated by application 3, there are 2 unread notifications left.

    In the second sample test:

    1. Application 2 generates a notification (there is 1 unread notification).
    2. Application 4 generates a notification (there are 2 unread notifications).
    3. Application 2 generates a notification (there are 3 unread notifications).
    4. Thor reads first three notifications and since there are only three of them so far, there will be no unread notification left.
    5. Application 3 generates a notification (there is 1 unread notification).
    6. Application 3 generates a notification (there are 2 unread notifications).

    自己做的时候没想到用队列, 我只想到了从3到2的影响的解决方案,想不出来从2的到3的解决方案。QAQ

    本题用队列做。

    对于1,用sum队列记录每个进入的编号 cnt++,同时每个应用也要开的队列,把此编号加入到每个应用的队列中。

    对于2,开一个used数组,如果used[vis[y].front()]=0,那么此条消息没看过,更新used值,ans++, pop。

    对于3,从总的队列sum出,直到队列为空或者当前编号小于y。

    结果cnt-ans.

     1 #include <iostream>
     2 #include <cstdio>
     3 #include <cstring>
     4 #include <algorithm>
     5 #include <vector>
     6 #include <map>
     7 #include <queue>
     8 using namespace std;
     9 const int maxn = 3e5+5;
    10 queue<int> sum,vis[maxn];
    11 int used[maxn];
    12 int main()
    13 {
    14     int n,q;
    15     cin>>n>>q;
    16     int ans = 0;
    17     int cnt = 0;
    18     int x,y;
    19     for(int i=1;i<=q;i++)
    20     {
    21         scanf("%d %d",&x,&y);
    22         if(x==1)
    23         {
    24             cnt++;
    25             vis[y].push(cnt);
    26             sum.push(cnt);
    27         }
    28         else if(x==2)
    29         {
    30             while(!vis[y].empty())
    31             {
    32                 if(!used[vis[y].front()])
    33                 {
    34                     used[vis[y].front()] = 1;
    35                     ans++;
    36                 }
    37                 vis[y].pop();
    38             }
    39         }
    40         else
    41         {
    42             while(!sum.empty()&&sum.front()<=y)
    43             {
    44 
    45                 if(!used[sum.front()])
    46                 {
    47                     used[sum.front()] = 1;
    48                     ans++;
    49                 }
    50                 sum.pop();
    51             }
    52         }
    53         printf("%d
    ",cnt-ans);
    54     }
    55     return 0;
    56 }
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  • 原文地址:https://www.cnblogs.com/littlepear/p/5851160.html
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