## CCC '15 J4 - Wait Time

View as PDF

Points: 5
Time limit: 2.0s
Memory limit: 64M

Problem type
##### Canadian Computing Competition: 2015 Stage 1, Junior #4

You exchange text messages with your friends. Since you receive so many messages, you want to measure how long your friends have to wait for your replies.

Your message device records each received and sent message in order using the following two kinds of entries:

• R indicates a message was received from a friend numbered ;
• S indicates a message was sent to a friend numbered .

Your message device sends and receives messages instantaneously, and for each consecutive pair of entries described above, either

• a single entry W is recorded in between them indicating they occur seconds apart, or
• there is no entry between them and they occur one second apart

Several rules of message etiquette are always followed:

• the only messages you send are replies to messages that you have received;
• you send at most one reply to any message from any particular friend;
• your friends do not send a subsequent message until you have replied to their previous message.

The wait time for a message is the time that passes between when you receive it and the time you reply to it. If a friend received a reply to each message they sent, the total wait time for friend is the sum of all wait times for all messages from friend X. Otherwise, the total wait time for friend X is .

Your job is to determine the total wait time for each friend.

#### Input Specification

The input consists of the integer (), followed by lines, where each line consists of one character (W, R, or S), followed by a space, followed by an integer (). These lines are the entries described above (in order).

#### Output Specification

Output one line for each friend that sent a message in the form where is a friend number and is the total wait time for friend . The lines are in increasing order of the friend numbers.

#### Sample Input 1

5
R 2
R 3
W 5
S 2
S 3

#### Output for Sample Input 1

2 6
3 6

#### Explanation of Output for Sample Input 1

Friend sends a message at time and Friend sends a message at time . Friend receives a reply at time and Friend receives a reply at time .

#### Sample Input 2

14
R 12
W 2
R 23
W 3
R 45
S 45
R 45
S 23
R 23
W 2
S 23
R 34
S 12
S 34

#### Output for Sample Input 2

12 13
23 8
34 2
45 -1

#### Explanation of Output for Sample Input 2

For Friend , a message is received at time and replied to at time . For Friend , two messages are exchanged, with the first message having a wait time of seconds and the second message having a wait time of seconds. For Friend , a message is received at time and replied to at time . Friend sends a message which is never replied to.

• lele  commented on Dec. 30, 2018, 7:39 p.m. edited

I'm confused even with the explanations Edit:

I read it over and now I know how it works. Sorry to waste your time.

• Raymond2031  commented on May 27, 2018, 9:46 a.m.

guys i tried to friend y'all in life but none of y'all had an account

• shinigamiking100  commented on Feb. 19, 2017, 11:24 a.m.

In the sample output, it shows "2 6" and "3 6" yet the explanation states that it should be "2 6" and "3 7".

(This is for sample output 1)

• Kirito  commented on Feb. 19, 2017, 11:47 a.m.

This typo was present on the official PDF as well. (Waterloo double check your work plz -.- )

It has been fixed (at least on our site).

• JJ_G4M3R  commented on Nov. 27, 2018, 11:29 p.m.

I don't believe it is a typo. When a reply was sent to friend 3, it was time 7. The only reason the output is "3 6" is because the message from friend 3 was received at time 1 (first message counts as time 0). This logic carries through to the explanation of sample input 2.

• felixzhang25  commented on Oct. 10, 2018, 9:12 p.m.

Yeah, on wcipeg it still says:

Explanation of Sample 1 Friend 2 sends a message at time 0 and Friend 3 sends a message at time 1. Friend 2 receives a reply at time 6 and Friend 3 receives a reply at time 7.

so it is probably only fixed here!!!

• DKLS2  commented on Jan. 17, 2017, 10:37 a.m. edit 2

when you receive it and the time you reply to it If...

It should be : when you receive it and the time you reply to it. If...

• Kirito  commented on Jan. 17, 2017, 11:17 a.m.

Fixed. Thanks for pointing that out!