Alice and Bob play the following coins-on-a-stack game. 20
coins are stacked one above the other. One of them is a
special (gold) coin and the rest are ordinary coins. The
goal is to bring the gold coin to the top by repeatedly
moving the topmost coin to another position in the stack.

Alice starts and the players take turns. A turn consists of
moving the coin on the top to a position i below the top
coin (0 = i = 20). We will call this an i-move (thus a 0-
move implies doing nothing). The proviso is that an i-move
cannot be repeated; for example once a player makes a 2-
move, on subsequent turns neither player can make a 2-move.
If the gold coin happens to be on top when it's a player's
turn then the player wins the game. Initially, the gold
coinis the third coin from the top

Answer Posted / teena

alice can take either a 0move or a 1 move.

initially if alice take 0 then bob take 1.. which means there are still 2 coins above the gold coin... the same is true when alice takes 1 and bob take zero...

after this alice choise must be 2.. so there is one coin above the gold coin... so then watever choice bob makes brings the coin to position 1...

ao alice is the winner

Is This Answer Correct ?    29 Yes 13 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

There are two balls touching each other circumferentially. The radius of the big ball is 4 times the diameter of the small ball.The outer small ball rotates in anticlockwise direction circumferentially over the bigger one at the rate of 16 rev/sec. The bigger wheel also rotates anticlockwise at N rev/sec. what is 'N' for the horizontal line from the centre of small wheel always is horizontal.

1043


I bought a car with a peculiar 5 digit numbered licence plate which on reversing could still be read. On reversing value is increased by 78633. Whats the original number if all digits were different?

907


f(X)= 2X-1 + f(X-1) if X is not equal to zero and if f(X=0)=0, If f(X)=4f(X-1) then the value of X=?

684


Two trains are traveling in 60 kmph on same trace, towards each other. When the distance between them is 18 km, a fly is going to start, flying between them in 80 kmph speed. Find the traveling path distance of the fly upto when it is going to crush by the 2 trains?

694


if a,b>0 and a+b=2 then the max value of ab is

769






in a question ,last part has, the ages of two people has the ratio of 6:6 and by adding the numbers we get 44, after how many years the ratio would be 8:7?

841


If a man can swim downstream at 6kmph and upstream at 2kmph, his speed in still water is: It takes 30 days to fill a laboratory dish with bacteria. If the size of the bactiria doubles each day, how long did it take for the bactiria to fill one half of dish?

938


ABCE is an isosceles trapezoid and ACDE is a rectangle. AB = 10 and EC = 20. What is the length of AE?

1544


A coffee shop blends 2 kinds of coffee,putting in 2 parts of a 33p. a gm. grade to 1 part of a 24p. a gm.If the mixture is changed to 1 part of the 33p. a gm. to 2 parts of the less expensive grade,how much will the shop save in blending 100 gms.

985


it has 20 mixutre conatins mil and water in the ratio 3:5,replace 4 litres of mixture with 4 litres of water what is the final ratio of milk and water.

907


Alok and Bhanu play the following min-max game. Given the expression N = X - Y – Z where X, Y and Z are variables representing single digits (0 to 9), Alok would like to maximize N while Bhanu would like to minimize it. Towards this end, Alok chooses a single digit number and Bhanu substitutes this for a variable of her choice (X, Y or Z). Alok then chooses the next value and Bhanu, the variable to substitute the value. Finally Alok proposes the value for the remaining variable. Assuming both play to their optimal strategies, the value of N at the end of the game would be • 4 • -18 • 9 • 2

2160


A car is filled with four and half gallons of fuel for a round trip.If the amount of fuel taken while going is 1/4 more than the amount taken for coming, what is the amount of fuel consumed while coming back?

935


In Madras, temperature at noon varies according to -t^2/2 + 8t + 3, where t is elapsed time. Find how much temperature more or less in 4pm to 9pm.

926


How many ways can one arrange the word EDUCATION such that relative positions of vowels and consonants remains same?

848


A man drives at a speed of 40 miles/hr. His wife left 30 mins. late with 50 miles/hr speed. when will they meet ?

1209