Sorry, should have done it on paper properly!! Thanks!
PS: below is the mail which I was about to write thinking that total time would not be 30 minutes if we burn it from both ends. Ok Suppose the length is 60meters. For 0-L/2 we have burn rate of 2/3m per minute. So, total time L/2/(2/3)= 45minutes. And for L/2 to L, we have burn rate of 2m per min. So, Time for burning 30-60 meters is 15 minute. Suppose, we light up both the ends. Then After 15 minutes, L/2-L portion will be completely burn. And For 0-L/2 portion, we would have burn total 2/3*15= 10meters. Now, You are left with 10-30 (i.e total of 20 meter string) and it is burning at both ends after 15 minutes. So, remaining string will burn in (20)/(2*2/3) time i.e 15 minutes. Shit :\ On Sun, Jul 10, 2011 at 1:02 AM, Dumanshu <[email protected]> wrote: > The above posted solution is independent of the burning rate. I am not > counting the minutes using the half burnt string. Instead, the fire is > running and when the whole string is burnt, I am using the time. > > Say u light up a string from both ends, then irrespective of burn rate > it should give 30 min. Because we have the choice to lit the string > from either end and it burns completely in 1 hour. > > On Jul 9, 10:09 pm, "oppilas ." <[email protected]> wrote: > > Yes, these solution are valid. But for them the burning rate of each > string > > must be constant. > > Each piece of string takes exactly an hour to burn, but the burn rate is > not > > constant > > Can't we have a string which take 45 minutes to burn till half length. > > 0-L/2. And 15 min from L/2 to L. > > > > > > > > > > > > > > > > On Sat, Jul 9, 2011 at 8:57 PM, Dumanshu <[email protected]> wrote: > > > @oppilas: > > > > > light the first string at both ends and in the middle. So it will burn > > > completely in 15 min as the fire is advancing in 4 ways irrespective > > > of the burn rate. > > > when the first string is completely burnt, light the second string at > > > both ends to get another 30 min. So, overall 45 min. > > > > > On Jul 9, 5:11 am, "oppilas ." <[email protected]> wrote: > > > > You have 2 pieces of string of different, unspecified length, and > some > > > > matches. Each piece of string takes exactly an hour to burn, but the > burn > > > > rate is not constant. . The strings have different burn rates, and of > > > course > > > > you don't know the rates anyway. > > > > > > Using only the matches and the strings, measure 45 minutes. > > > > > > I have thought a lot but unable to find a solution for this problem. > Can > > > > someone please try it. > > > > > -- > > > You received this message because you are subscribed to the Google > Groups > > > "Algorithm Geeks" group. > > > To post to this group, send email to [email protected]. > > > To unsubscribe from this group, send email to > > > [email protected]. > > > For more options, visit this group at > > >http://groups.google.com/group/algogeeks?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/algogeeks?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
