Four people are stuck on one side of the bridge and opposition Army is approaching to kill them. They should cross the bridge in minimum time possible. Crossing time needed for each. Soldier - 1 Min Gunman - 2 Min King - 5 Min Queen - 10 Min Torch ( As much as by the person carrying it ) Conditions: Only 2 people can cross the bridge as its not well built. Torch should be always with somebody when crossing as its dark. Torch cannot be thrown as bridge is wider than any human can throw the torch on other side. Time taken by 2 persons are of the one who is slowest.
This is a famous puzzle [See : http://en.wikipedia.org/wiki/Beatles_Concert_Puzzle] I think the optimal solution is : TIME xxxxxx MOVEMENT 0+2xxxxxxxxxSoldier and Gunman move to opposite side. 2+1xxxxxxxxxSoldier comes back. 3+10xxxxxxxxKing and Queen move to opposite side. 13+2xxxxxxxxGunman comes back. 15+2xxxxxxxxSoldier and Gunman move to opposite side. 17xxxxxxxxxxAll have crossed safely So, minimum time to cross is 17 mins :hurray:
The other solution would be that Gunman comes first and Soldier comes later. But in any case, 17 would be the minimum time taken for all to cross the bridge. Nice Reply Saswat.:2thumbsup
I knew about this but I changed and framed the question a bit different hoping Saswat would not know it
