#P3726. Cheating Coin Toss Showdown
Cheating Coin Toss Showdown
Cheating Coin Toss Showdown
Little A and Little B are close friends who often play games together. Recently, Little B has been obsessed with a mobile gacha game and spends every day grinding, yet not once has he managed to get an SSR. Frustrated, Little B begins to doubt his life choices. Meanwhile, Little A—no stranger to a losing streak—decides to convince Little B to give up the game and focus on studying. He proposes a coin tossing challenge: both toss b
coins, and Little A wins if the number of heads he gets is greater than the number of heads Little B gets.
However, having once suffered through his own misadventures in a similar game, Little A is not fully confident in his luck. So, while Little B isn’t looking, Little A secretly cheats by tossing an extra r
coins. In other words, Little A tosses a total of b + r
coins, while Little B tosses only b
coins. Let the number of heads obtained from Little A’s initial b
tosses be \(X\), the number of heads from his extra r
tosses be \(Y\), and Little B’s number of heads be \(Z\). Then Little A wins if and only if
\[
X + Y > Z.
\]
Your task is to calculate the total number of possible outcomes (each coin toss having 2 equally likely outcomes) in which Little A wins. Since the answer might be very large, output the last \(k\) digits of the answer. If the result has fewer than \(k\) digits, pad it with leading zeros.
Note: The total number of outcomes is \(2^{(2b+r)}\) because Little A tosses \(b+r\) coins and Little B tosses \(b\) coins.
inputFormat
The input consists of three space‐separated integers:
b
: the number of coins both players initially toss,r
: the number of extra coins tossed by Little A,k
: the number of digits to output (i.e. output the last \(k\) digits, padding with leading zeros if necessary).
outputFormat
Output a single string representing the last \(k\) digits of the total number of winning outcomes for Little A.
sample
1 0 2
01