208 - Firetruck

[kjus]

For those who have WA :
actually, the different paths must be output in lexicographic order.

[ishtiaq ahmed]

I have no idea why it is TLE. Please try to help me. Here is my code

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/*
		Problem No: 208
		Problem : Firetruck 
		Algorithm: DFS
		Author : Ishtiaq Ahmed
*/

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<stdlib.h>
#include<ctype.h>
#include<iostream>
#include<algorithm>
using namespace std;

#define maximum(aa, bb) ((aa) > (bb) ? (aa) : (bb))



int destination;
int counting = 0;
bool array[1000][1000] = {false};
bool visited[1000] = {false};
int result[1000], indexx;


void DFS(int current, int max){
	int i;
	if(current == destination){
		result[++indexx] = current;
		for(i = 0; i <= indexx; i++){
			if(indexx == i)
				printf("%d\n", result[i]);
			else
				printf("%d ", result[i]);
		}
		counting++;
		return;
	}
	result[++indexx] = current;
	visited[current] = true;
	for(i = 1; i <= max; i++){
		if(array[current][i] == true && visited[i] == false){
			DFS(i, max);
			visited[i] = false;
			indexx--;
		}
	}
}





int main(){
	//freopen("c:\\input.txt", "r", stdin);
	//freopen("c:\\out.txt", "w", stdout);

	int casno = 0, i, j, a, b;
	int max = -99999;
	while(scanf("%d", &destination) != EOF){
		printf("CASE %d:\n", ++casno);
		counting = 0; 
		indexx = -1;
		for(i = 1; i <= max; i++)
			for(j = 1; j <= max; j++)
				array[i][j] = false;
		
		for(i = 1; i <= max; i++)
			visited[i] = false;
		max = -9999999;
		while(scanf("%d %d", &a, &b)){
			if(!a && !b)
				break;
			array[a][b] = true;
			array[b][a] = true;
			max = maximum(max, a);
			max = maximum(max, b);

		}
		
		
		DFS(1, max);
		printf("There are %d routes from the firestation to streetcorner %d.\n", counting, destination);
	}
	return 0;
}

[newton]

Mr Ishtiaq try to realize if there are 10000 nodes and a node Ni may have only 1 adj node. Your program may search 10000 times to find the adj node though it is possible to find it in O(1).

Try to use List or vector in STL.
May it help u.

[thales]

Actually, I can not understand the idea of prunning backtracking with Floyd.
In backtracking, if I arrived to a node A from which the final node T is unreachable, still Floyd will give value
less than infinite, since from A I can reach T with some node I already used.
So, Floyd will not reject the specific node since with the matrix I will not be able to know the nodes I need to travel
from A to T.
Thanks in advance for any help

[ryen]

I use backtrack to get the path, and pruning the nodes that cannot get to the dest. But I always get WA, could anybody give me some critical I/O?
here is my code below:

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removed after ACed.

[ryen]

I've found the bug, and got Aced.

[4ndypanda]

Actually, I can not understand the idea of prunning backtracking with Floyd.
In backtracking, if I arrived to a node A from which the final node T is unreachable, still Floyd will give value
less than infinite, since from A I can reach T with some node I already used.
So, Floyd will not reject the specific node since with the matrix I will not be able to know the nodes I need to travel
from A to T.
Thanks in advance for any help

You're right assuming the graph is undirected. In reality it is undirected for every vertex except 1. However, I didn't take that into account and I still got accepted. My only guess is that they have a test case where 1 is part of a complete graph with 18 other nodes and the fire happens to be at the one node that is unreachable. I think my code would have timed out if they had connected that fire to the fire station since Floyd Warshall would compute a path from any vertex to the fire due to undirected paths

[Imti]

TLE:
All the above posts about TLE and how to optimize it.But I am still getting TLE in following code.Please Help anyone...

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Code Removed

Finally Got Acc..I didn't notice sohel's stated tricks..thanks sohel nd also thanks goes to Sedefcho for his nice explanation...

[Zippie72]

thanks, that helped me a lot!
regards,
chantal

[@li_kuet]

Who are getting TLE
Just use floyed-warshall to check if it is possible to reach the destination via current streetcorner
if not then simply return else backtrack

Who are getting WA
Output must be in sorted order.
like >>
if there are two paths to 6
(1 5 3 6) and (1 4 2 3 6)
then output must be

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1 4 2 3 6
1 5 3 6
There are 2 routes from the firestation to streetcorner 6.

[brianfry713]

Input:

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14
1 8
2 11
3 4
3 6
4 14
5 6
5 8
6 11
6 12
8 14
9 14
10 14
11 14
0 0

AC output:

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CASE 1:
1 8 5 6 3 4 14
1 8 5 6 11 14
1 8 14
There are 3 routes from the firestation to streetcorner 14.

[Scarecrow]

AC

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AC

[brianfry713]

Your output is not sorted correctly for the sample input.

[Scarecrow]

Thanks Brianfry713! I thought any ordering of the routes would be fine as in the problem statement there's no mentioning of sorting the routes.

[brianfry713]

See:
http://uva.onlinejudge.org/index.php?op ... category=4

208 has a green check so there is only one acceptable output. Your code should match the sample I/O exactly. On the problems with a yellow check there is a special judge and it may accept multiple correct outputs.