10129 - Play on Words

[Rossi]

I think its simple Euler tour testing .
but getting wrong answer.....

[LittleJohn]

The graph may be disconnected, did you do this check?

[Mohammad Mahmudur Rahman]

I think this is an easy problem where all I need to do is to detect the presence of an euler path in a directed graph. But I am getting repeated WA for apparantly no reason. Can someone give me some tricky I/O please? Thanks in advance.

[sidky]

The problems doesn't have any tricky inputs. Have you checked whether the graph is connected?

[Mohammad Mahmudur Rahman]

Have you checked whether the graph is connected?

Yes, I did. The problem is somewhere else. I think I am missing something & hence should recode it from the scratch.

[Mohammad Mahmudur Rahman]

Well, recoding worked. I've got AC though couldn't figure out the problem in the previous version. . Thanks to you, Sidky for your suggestion.

[backjack02]

Here is my code, why do I always get wrong answer?
Where is my problem?


#include <stdio.h>
4 #include <stdlib.h>
5
6 int main(int argc, char **argv)
7 {
8 long long t, n;
9 int i, j, ctn, flag;
10 char c, link;
11 char *check;
12 check=(char *)malloc(sizeof(char)*1001);
13
14 scanf("%lld%c", &t, &c);
15 for(i=0; i<t; i++){
16 scanf("%lld%c", &n, &c);
17 if(n<1 || n>100000)
18 return 0;
19 flag=1;
20 for(j=0; j<n; j++){
21 ctn=0;
22 while((c=getchar())!='\n'){
23 if(c==EOF)
24 return 0;
25 check[ctn]=c;
26 ctn++;
27 }
28 check[ctn]='\0';
29 if(ctn<2 || ctn>1000)
30 return 0;
31
32 if(j>0){
33 if(check[0]!=link)
34 flag=0;
35 }
36
37 link = check[ctn-1];
38 }
39 if(flag==1)
40 printf("Ordering is possible.\n");
41 else
42 printf("The door cannot be opened.\n");
43 }
44 return 0;
45 }

[..]

You have wrong understanding on the problem.
It is asked "whether it is possible to arrange all of the plates in a sequence"

You can arrange the order of word, so for
2
abc
xxa
The answer is "possible".

[backjack02]

I got it!
Thank you:-)

[akiha]

All the variable and array are well defined
no pointer is used

why segmentation fualt?.............orz

THZ for any reply

[..]

There are many ways to get segmentation fault.
Although you say array are well defined, how do you ensure that without knowing judge input?
In my opinion, there is only one way to ensure it, when you access any array, say a, you check if i < 0 or i > max. bound, if yes, then you crash the program by i = 1 / 0 (floating point error)

Always check your program with boundray case, for either N = 1 or 100000, you have to check if your program can passes such case by TESTING. Don't just read your code and then think it will pass.

Some other way of segmentation fault is "stack overflow". Say for this C program:

Code: Select all

re() {
   int i;
   re();
}

main() {
   re();
}

The endless recursion will get stack overflow and give you segmentation fault. Check if your program will get endless recursion.

[akiha]

Code: Select all

#include <stdio.h>
#include <string.h>

main(void)
{       
	char in[1000];
	int head[26];
	int tail[26];
	int con[26][26];
	int check[26];
	int g[3];
	int n=0;
	int a,b,i,j,m,t,count,p,q;
	int s=0;
	int cb=0;
	char prichk='0';
	char secchk='0';
	char terchk='0';
	char finalchk='0';
	char finalchk2='0';
	char netio='0';
	
	scanf ("%d\n" ,&t);

	for (m=0;m<t;m++)
	{

		for (b=0;b<27;b++)
		{
			head[b]=0;
			tail[b]=0;
			check[b]=0;
		}
		printf("%d%d%d\n",head[26],tail[26],check[26]);

		for (b=0;b<27;b++)
		{
			for (a=0;a<27;a++)
			{
				con[b][a]=0;
			}
		}

		g[0]=-1;
		g[1]=-1;
		g[2]=0;
		
		scanf ("%d\n" ,&s);

		for (count=0;count<s;count++)
		{
			gets (in);
			n = strlen(in);

                                                  -SKIP-
                                 }
	}
	return 0;
}

I CHECK ALL THE BOUND
I SEEMS NO PROBLEM......OTZ

[..]

Code: Select all

#include <stdio.h>
	int head[26];
	int tail[26];
	int con[26][26];
	int check[26];

		for (b=0;b<27;b++)
		{
			head[b]=0;
			tail[b]=0;
			check[b]=0;
		}
		printf("%d%d%d\n",head[26],tail[26],check[26]);

CERTAINLY IT HAS PROBLEM!
for "int tail[26]", the elements are numbered from 0 to 25

[akiha]

I KNOW THAT

BUT WHEN I SET B<26
IT ALSO SEGMENTATAION ERROR

[..]

Similar mistake here:
char in[1000];
To hold a string of 1000 chars long, the array size should NOT be 1000.