Problem 1159. Coin Tossing: Probability of Same Heads for N tosses

Created by Richard Zapor

Solve Later

A pair of physicists toss a coin n times each.

What is the probability that they tossed the same number of heads?

Input: N % number of tosses

Output: P

Examples:

N=1 P=0.5;

N=2 P=0.375

Test Suite will round to 6 places

Solve

Solution Stats

78 Solutions
33 Solvers

Last Solution submitted on Mar 23, 2020

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Solution 184390

1 Comment

1 Comment

Tim on 2 Jan 2013

This fails for test case 4 even though it is mathematically correct--it gives 0.27343749999999994 instead of 0.2734375, while the test suite asks for 0.273438; it seems as though a fair test generally has to be of the form abs(y-y_correct)<tol*abs(y_correct); rounding to some number of decimal places always allows for possibilities like this. (Not a complaint, just a point of interest.)

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coin nchoosek probability