HackerEarth: first algorithm practice - Milly Chocolate

Feb. 26, 2016

Spent more than 1 hour to work on an algorithm problem on HackerEarth.

Problem statement:
https://www.hackerearth.com/druva-sdet-hiring-challenge/algorithm/milly-and-chocolates-4/

Milly loves to eat chocolates. She buys only those food items which contain some amount or percentage of chocolate in it. She has purchased N such food items and now she is planning to make a new food item by her own. She will take equal proportions of all of these N food items and mix them. Now she is confused about the percentage of chocolate that this new food item will have. Since she is busy in eating the chocolates so you have to help her in this task.

Input

First line of the input will contain T (no. of test cases). Every test case will contain two lines. First line will contain N (no. of food items) and the second line will contain N space separated P_i values denoting the percentage of chocolate in i^th food item.

Output

For every test case, print the percentage of chocolate that will be present in the new food item.

Note : Your answer should be exactly up to 8 decimal places which means that if your answer is 2.357 then you have to print 2.35700000 or if your answer is 2.66666666 .... then you have to print 2.66666667

Constraints

1 <= T <= 5
1 <= N <= 5*10⁵
0 <= P_i <= 100

SAMPLE INPUT

1
3
80 30 90

SAMPLE OUTPUT

66.66666667

Time Limit: 1 sec(s) for each input file.

Memory Limit: 256 MB

Source Limit: 1024 KB

Marking Scheme: Marks are awarded if any testcase passes.

Allowed Languages: C, CPP, CLOJURE, CSHARP, GO, HASKELL, JAVA, JAVASCRIPT, JAVASCRIPT_NODE, LISP, OBJECTIVEC, PASCAL, PERL, PHP, PYTHON, RUBY, R, RUST, SCALA

Julia's practice:
1 second for each file, but, the time is over 1 second. Need to work on speed! (Julia likes the challenge! )

https://github.com/jianminchen/hackerEarth/blob/master/MillyandChocolates/MillyAndChocolate.cs

Julia read editorial of algorithm, and know the better solution:

https://www.hackerearth.com/problem/algorithm/milly-and-chocolates-4/editorial/
(will try her own version as well later. Definitely, the code will take less time to write! Good learning tool - Thanks, hackerEarth!)

So, to fix TLE error ( more than 1 second for each file), Julia wrote a bug free version:
https://github.com/jianminchen/hackerEarth/blob/master/MillyandChocolates/MillyAndChocolate_BugFix.cs

Read this web page:

https://www.hackerearth.com/@pranjuldb/activity/hackerearth/

Julia's hackerEarth profile:

https://www.hackerearth.com/@jianminchen.fl