# HackerRank ‘Halloween Sale’ Solution

##### Short Problem Definition:

You wish to buy video games from the famous online video game store Mist.

Usually, all games are sold at the same price, *p *dollars. However, they are planning to have the seasonal Halloween Sale next month in which you can buy games at a cheaper price. Specifically, the first game you buy during the sale will be sold at dollars, but every subsequent game you buy will be sold at exactly *d* dollars less than the cost of the previous one you bought. This will continue until the cost becomes less than or equal to *m* dollars, after which every game you buy will cost *m* dollars each.

##### Link

##### Complexity:

time complexity is O(1)

space complexity is O(1)

##### Execution:

The solution is based on the Arithmetic Progression. It makes it a bit more complex due to the floor *m*.

Another option is either a while loop or a recursion.

##### Solution:

// Complete the howManyGames function below. int howManyGames(int p, int d, int m, int s) { int n=floor( (p-m)/d +1); if( (n*(2*p-(n-1)*d))/2 <= s) { return n + (s-(n*(2*p-(n-1)*d)/2))/m; } else { return floor(((-d-2*p)+sqrt((-2*p-d)*(-2*p-d)-(8*d*s)))/(-2*d)); } }

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