Added reference to HackerRank Fundamental Mathematics Problem 'Army Game'.
Added reference to HackerRank Fundamental Mathematics Problem 'Army Game'.

shivkrthakur/HackerRankSolutions,shivkrthakur/HackerRankSolutions,shivkrthakur/HackerRankSolutions,shivkrthakur/HackerRankSolutions