10681 - Teobaldo's Trip

All about problems in Volume 106. If there is a thread about your problem, please use it. If not, create one with its number in the subject.

Moderator: Board moderators

User avatar
sohel
Guru
Posts: 856
Joined: Thu Jan 30, 2003 5:50 am
Location: New York

Post by sohel » Mon Aug 23, 2004 6:27 am

Accepted.

I modified my bfs() and got it AC in 0.04 seconds.
Larry wrote: Use dynamic programming by first finding a recurrence..
Can someone give some detail about this recurrence relation. I think most of the people used Larry's method.

tep
New poster
Posts: 23
Joined: Fri Jun 13, 2003 6:08 am
Contact:

Post by tep » Mon Aug 23, 2004 3:59 pm

I use memoization / dp approach. Here is some clue

memo[v][d]
can i reach the destination if i'm vertex no v and i have d days left.

I'm sure you can figure out the rest

regards,
stephanus

daveon
Experienced poster
Posts: 229
Joined: Tue Aug 31, 2004 2:41 am
Location: TORONTO, CANADA

10681 Teobaldo's Trip

Post by daveon » Thu Sep 01, 2005 4:16 am

Here is a tricky case.

INPUT:

Code: Select all

3 2
1 2
2 3
2 2 0
OUTPUT:

Code: Select all

Yes, Teobaldo can travel.

User avatar
Rocky
Experienced poster
Posts: 124
Joined: Thu Oct 14, 2004 9:05 am
Contact:

10681 Problem..

Post by Rocky » Fri Nov 25, 2005 6:30 am

I Get WA For This Problem....
Can Any One Give Me Some Tricky Case.....

Thank's In Advance
Rocky

daveon
Experienced poster
Posts: 229
Joined: Tue Aug 31, 2004 2:41 am
Location: TORONTO, CANADA

Post by daveon » Mon Dec 26, 2005 12:50 am


User avatar
Rocky
Experienced poster
Posts: 124
Joined: Thu Oct 14, 2004 9:05 am
Contact:

Thank's..

Post by Rocky » Sun Jan 01, 2006 7:15 am

Thank's....

Rocky

helloneo
Guru
Posts: 516
Joined: Mon Jul 04, 2005 6:30 am
Location: Seoul, Korea

10681 Teobaldo's Trip again.. Tell me what's wrong..!!

Post by helloneo » Thu Jan 05, 2006 6:01 pm

if Teobaldo can go j city on i-th day, i check dp[j] = i
it's kind of straightforward.. but getting WA..
plz tell me what's wrong..


Code: Select all

code removed
Last edited by helloneo on Sun Aug 06, 2006 7:43 am, edited 1 time in total.

medv
Learning poster
Posts: 85
Joined: Sun Jul 14, 2002 1:17 pm

Try this input

Post by medv » Sun Feb 19, 2006 6:29 pm

Try this input:

2 1
1 2
1 2 3

your program gives NO, but must be YES.
The trip is: 1 - 2 - 1 - 2

asif_rahman0
Experienced poster
Posts: 209
Joined: Sun Jan 16, 2005 6:22 pm

Post by asif_rahman0 » Sat Apr 01, 2006 9:55 am

i m not expert in DP
so i think u can use easily matrix multiplication for finding link between vertices. which is O(n^3).
then use another loop for days....then it would be O(n^4) by some extra checking. get it aceepted within 1.4/1.3

hope it helpssssssss. :)

N.B: dont use map[days][j] = map[days][j] | ( map[days][k]&map[days][k][j])

use IF condition for faster Running Time

Darko
Guru
Posts: 580
Joined: Fri Nov 11, 2005 9:34 am
Location: Calgary, Canada

Post by Darko » Fri Aug 04, 2006 11:31 pm

I guess I don't understand this problem...
What would be the output for

Code: Select all

2 1
1 2
1 2 4
I think it's "No", because he can't make that trip in exactly 4 days?

mf
Guru
Posts: 1244
Joined: Mon Feb 28, 2005 4:51 am
Location: Zürich, Switzerland
Contact:

Post by mf » Sat Aug 05, 2006 12:02 am

That's right. Output is "No" if and only if there is no trip of length exactly D days.

Shafaet_du
Experienced poster
Posts: 147
Joined: Mon Jun 07, 2010 11:43 am
Location: University Of Dhaka,Bangladesh
Contact:

Re: 10681 - Teobaldo's Trip

Post by Shafaet_du » Tue Jun 07, 2011 10:19 pm

I solved using dp but i am interested to know the matrix exponent solution. I am failing to raise the power to 200 as the elements are becoming too large. Do we need to use some kind of modular arithmetic?

pranon
New poster
Posts: 14
Joined: Mon Jul 23, 2012 2:39 pm

Re: 10681 - Teobaldo's Trip

Post by pranon » Wed Jul 25, 2012 10:49 pm

Code being judged ``WA" with me having no idea why. Any help in pointing out would be much appreciated.

Code: Select all

[code]
#include <stdio.h>
#include <string.h>

char mat[105][105], adj[105][105], temp[105][105], city[105];
char ytic[100000];


int main()
{
    int c, l, j, i, a, b, s, e, d, t, k;
    while(scanf("%d %d", &c, &l)==2 && (c || l))
    {
        j=0;
        while(l--)
        {
            scanf("%d %d", &a, &b);
            if(ytic[a]==0)
            {
                city[j]=a;
                ytic[a]=j++;
            }
            if(ytic[b]==0)
            {
                city[j]=b;
                ytic[b]=j++;
            }
            adj[ytic[a]][ytic[b]]=adj[ytic[b]][ytic[a]]=mat[ytic[a]][ytic[b]]=mat[ytic[b]][ytic[a]]=1;
        }
        scanf("%d %d %d", &s, &e, &d);
        t=1;
        s=ytic[s];
        e=ytic[e];
        while((t<<1)<=d)
        {
            for(i=0; i<c; i++)
                for(j=0; j<c; j++)
                    for(k=0; k<c; k++)
                        if(mat[i][k]>0 && mat[k][j]>0)
                            temp[i][j]=1;
            for(i=0; i<c; i++)
                for(j=0; j<c; j++)
                    mat[i][j]=temp[i][j];
            t<<=1;
        }
        while(t<d)
        {
            for(i=0; i<c; i++)
                for(j=0; j<c; j++)
                    for(k=0; k<c; k++)
                        if(mat[i][k]>0 && adj[k][j]>0)
                            temp[i][j]=1;
            for(i=0; i<c; i++)
                for(j=0; j<c; j++)
                    mat[i][j]=temp[i][j];
            t++;
        }
        (mat[s][e]>0 ||(s==e && d==0))?printf("Yes, Teobaldo can travel.\n"):printf("No, Teobaldo can not travel.\n");
        for(i=0; i<c; i++)
        {
            memset(mat[i], 0, c*sizeof(char));
            memset(adj[i], 0, c*sizeof(char));
        }
        memset(city, 0, c*sizeof(char));
    }
    return 0;
}

[/code]
Thanks in advance. :(

mostafiz93
New poster
Posts: 31
Joined: Thu Nov 24, 2011 12:08 am

Re: 10681 - Teobaldo's Trip

Post by mostafiz93 » Thu Feb 14, 2013 12:29 am

I'm getting WA in this problem.

My algo is : first make adjacency matrix with the given liunks. then journey is possible if [adj matrix]^d is nonzero.

i've implemented this with matrix exponentiation.

Can anybody help me?

my code is here:

Code: Select all

removed after AC

sdipu
New poster
Posts: 23
Joined: Sun May 19, 2013 1:50 am

Re: 10681 - Teobaldo's Trip

Post by sdipu » Thu Jul 24, 2014 7:54 am

When you are solving this problem using matrix exponentiation, don't forget to use modulo operation.
Try this-

input:

Code: Select all

3 2
1 2
2 3
3 1 200

5 7
1 5
2 4
3 5
1 3
2 4
3 2
2 5
3 4 200

0 0
output:

Code: Select all

Yes, Teobaldo can travel.
Yes, Teobaldo can travel.
Check out UVA Arena - a software build for UVA solvers @ http://dipu-bd.github.io/UVA-Arena/

Post Reply

Return to “Volume 106 (10600-10699)”