12468 - Zapping
Problem H. Zapping
I’m a big fan of watching TV. However, I don’t like to watch a single channel; I’m constantly zapping between different channels.
My dog tried to eat my remote controller and unfortunately he partially destroyed it. The numeric buttons I used to press to quickly change channels are not working anymore. Now, I only have available two buttons to change channels: one to go up to the next channel (the △ button) and one to go down to the previous channel (the ▽ button). This is very annoying because if I’m watching channel 3 and want to change to channel 9 I have to press the △ button 6 times!
My TV has 100 channels conveniently numbered 0 through 99. They are cyclic, in the sense that if I’m on channel 99 and press △ I’ll go to channel 0. Similarly, if I’m on channel 0 and press ▽ I’ll change to channel 99.
I would like a program that, given the channel I’m currently watching and the channel I would like to change to, tells me the minimum number of button presses I need to reach that channel.
Input
The input contains several test cases (at most 200).
Each test case is described by two integers a and b in a single line. a is the channel I’m currently watching and b is the channel I would like to go to (0 ≤ a, b ≤ 99).
The last line of the input contains two -1’s and should not be processed.
Output
For each test case, output a single integer on a single line — the minimum number of button presses needed to reach the new channel (Remember, the only two buttons I have available are △ and ▽).
Sample input and output
standard input
standard output
3 9
0 99
12 27
-1 -1
6
1
15
Andrés Mejía-Posada, May 2012
#include<stdio.h>
int main(){ int a,b,c,d;while(scanf("%d%d",&a,&b)==2)
{ if(a<0 && b<0) { break;}
c=b-a;
if(a>b) {d=100-a+b;
}
else {d=100-b+a;
}
if(c<0) {c=c*(-1);
}
else if(d<0)
{d= d*(-1);
}
if(c>d) { printf("%d\n",d);}
else { printf("%d\n",c);}
}
return 0;}
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