10327 - Flip Sort

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10327 help

Post by route » Thu Dec 26, 2002 12:31 pm

junjieliang said that i can simply count the inversion....
but if the three swapping senetnces are omitted, i still got WA

Thus how can I "only count the inversions" ?

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Post by junjieliang » Fri Dec 27, 2002 10:31 am

Try this:

Code: Select all

inversion := 0;
for i := 1 to n-1 do
  for j := i+1 to n do
    if (m[i] > m[j]) then inc(inversion);
This should work. Btw there might be compile error (fix them yourself), since I typed this straight into the textbox...

Your code works as it is, I got AC in around 0:00:300. Just add a readln;
Good luck!

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10327 WA?????

Post by Jewel of DIU » Mon Nov 03, 2003 4:34 pm

Here is my code. I got WA in this problem.Where is my problem plz ?
----------- CUT AFTER AC ---------------
Last edited by Jewel of DIU on Sat Mar 20, 2004 3:55 pm, edited 1 time in total.
Hate WA
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Post by deddy one » Tue Nov 11, 2003 8:43 am

change your bubble function into like this

[cpp]int bubble(int n)
int i,j,count=0;
long temp;
if( n==0 !! n==1) return 0;

return count;

everything else seems fine.

you only need to count the exchange operations,
not to swap it.

I'm pretty sure that's the only problem here..

good luck

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Post by Algoritmo » Tue May 04, 2004 5:01 pm

First I thought this could be a complicated problem, but soon I wrote a 20 line code and got accepted at first submission.
Many ideas passed through my mind and I would like to share them with you.

Let's say we have an algorithim that flips adjacent numbers, but it's not optimal. What makes it non-optimal is the non-required flips it makes.

By the way, what is a non-required flip? It's any flip that's done towice (two numbers being fliped once and unflipped later).

An optimal algorithim does all the required flips but any of the non-required ones. So:
O = T - N
O: Optimal number of flips
T: Total number of flips an algorithim does
N: Non-required flips it does

So we can count the flips (T), discover which were non-required (N) and calculate the O.

But we can go further, because the non-required flips can be recognized without doing them. A non required flip is the one that will need to be undone. So it's a flip that puts a bigger number after a smaller one:
50 100
100 50 -> this flip will need to be undone

It's clear that the number N will always be a even number.

Note now that the number of required flips can also be identified. Look at the number 7 in the sequence below. With how many other numbers do you think it needs to flip?
The answer is simple, just count how many numbers greater than 7 exist at it's LEFT and now many numbers smaller than 7 exist at it's RIGHT. All of those need to be flipped with the number 7.

5 1 7 2 6 3 8 4 9

Now, forget about the 7 (or erase it) and do the same process with each one of the other numbers, and you have counted ALL of the REQUIRED flips you need to do :)

For an easy algorithim, start with the number X at left, count the required flips (how many numbers smaller than it exist on it's right) and forget about such number X.
Repeat this process untill you have "forgotten" all of them.
I solve 4 problems per day, then I expend 4 days stuck in a single problem. But I think I'm doing well... ID 37180

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Post by Piotrek Mazur » Tue Aug 10, 2004 11:43 pm

If I clearly understand you, this is finding the 'inversion number' (this algoritm works).

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10327 Why Gives Wrong Ans?Please Help

Post by efr_shovo » Thu Sep 30, 2004 7:22 am

Last edited by efr_shovo on Thu Sep 30, 2004 8:09 am, edited 1 time in total.

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Re: 10327 Why Gives Wrong Ans?Please Help

Post by efr_shovo » Thu Sep 30, 2004 8:07 am

I can't Under stand Why 10327 Gives Wrong Ans.
please help me.

here is my code.

#define MAX 1000

int n;
long item[MAX],temp,i,j,flip;

void main()

printf("Minimum exchange operations : %ld\n",flip);

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Post by Ghust_omega » Fri Oct 01, 2004 6:06 am

Hi !! efr_shovo your algo is not right you are counting the swaps of the selection algo, in this problem you have to count the swpas of the ......... well if I say I give the answer not :P so in that way try to think in one algo that make very swaps

Hope it helps
Keep posting !! :D

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Post by efr_shovo » Sat Oct 02, 2004 9:37 am

Thanks I have Now Accepted

Fuad Hassan_IIUC(DC)
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10327 why WA????

Post by Fuad Hassan_IIUC(DC) » Fri Feb 04, 2005 3:52 pm

plz help me :o
why WA?
int main()
long long n,data[10000],j,k,i,temp,swap;
else continue;
printf("Minimum exchange operations : %lld",swap);
return 0;

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emotional blind
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Post by emotional blind » Sat Feb 05, 2005 3:48 pm

your program doesnt output the minimum exchange
think about it

Code: Select all

4 3 2 1

Code: Select all

Minimum exchange operations : 2

but your program gives
Minimum exchange operations : 4

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Post by 59557RC » Mon May 09, 2005 2:48 pm

i dont understand why CE with this simple sortin code.anyone pls help.
int main()

int i,j,count,temp,c;
unsigned long a[1000];


for(i=0;i<c;i++) scanf("%lu",&a);


printf("Minimum exchange operations : %d\n",count);

return 0;

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Post by dumb dan » Mon May 09, 2005 3:17 pm

I'm guessing you're getting the following compile error:

conio.h: No such file or directory

conio.h is not part of the C standard. It is a Borland extension, and works only with Borland compilers (and perhaps some other commercial compilers)

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Post by J&Jewel » Wed May 11, 2005 12:36 pm

Yes Conio.h is reason for compile error..u can`t use it in the acm..
And u need not to declare array unsigned long i use int and got acc.
I hate Wrong Answer!

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