Hacker Rank problems solve by Erlang @Ahmah2009

common-divisors.erl

%% https://www.hackerrank.com/challenges/common-divisors/submissions/code/13608658
% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).
-compile(export_all).
main() ->
	{ok,[A]}=io:fread("", "~d"),
	scanner(A).
scanner(0)->
	ok;
scanner(N)->
	{ok,[A,B]}=io:fread("", "~d ~d"),
	solve(A,B),
	scanner(N-1).

rotate(List)->
	rotate(List,length(List)).
rotate(List,1)->
	[H|List1]=List,
	NewList=List1++[H],
	io:format("~s~n",[NewList]);

rotate(List,N)-> 
	[H|List1]=List,
	NewList=List1++[H],
	io:format("~s ",[NewList]),
	rotate(NewList,N-1).
solve(A1,B1)->
	A=solution:divisors(A1),
	B=solution:divisors(B1),
	AS=sets:from_list(A),
	BS=sets:from_list(B),
	ABS=sets:intersection(AS,BS),
	C=sets:size(ABS),
	io:format("~p~n",[C]).

divisors(N) -> 
	L=divisors(N, trunc(math:sqrt(N)), []),
	divisors_2(N,L).

divisors(_N, 0, D) -> D;
divisors(N, X, []) when N rem X == 0 -> divisors(N, X - 1, [X]);
divisors(N, X, []) when N rem X /= 0 -> divisors(N, X - 1, []);
divisors(N, X, D) when N rem X == 0 -> divisors(N, X - 1, [X|D]);
divisors(N,X,D) when N rem X /= 0 -> divisors(N,X-1,D).

divisors_2(N,Divisors)->
	Fun=fun(X,Acc)->
		Acc++[N div X]
	end,
	Divisors ++lists:foldl(Fun,[],Divisors).

eval-ex.erl

%% https://www.hackerrank.com/challenges/eval-ex/problem

% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).
-compile(export_all).
main() ->
	{ok,[A]}=io:fread("", "~d"),
	scanner(A).


scanner(0)->ok;

scanner(Tc)->
	{ok,[A]}=io:fread("", "~f"),
	R=solve(A),
	io:format("~.4f~n",[R]),
	scanner(Tc-1).


solve(X)-> 
	1 + 
	for_x(X,1) + 
	for_x(X,2) +
	for_x(X,3) +
	for_x(X,4) +
	for_x(X,5) +
	for_x(X,6) +
	for_x(X,7) +
	for_x(X,8) +
	for_x(X,9) .

for_x(X,I)->
	math:pow(X,I)/fact(I).

fact(0)->1;
fact(N)->N*fact(N-1).

fibonacci-fp.erl

%%https://www.hackerrank.com/challenges/fibonacci-fp/submissions/code/13629482

% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).
-compile(export_all).
main() ->
	{ok,[A]}=io:fread("", "~d"),
	solve(A).

solve(0)->
	ok;
solve(N)->	
	{ok,[A]}=io:fread("", "~d"),
	io:format("~p~n",[fib(A)]),
	solve(N-1).

fib(N)->
	fib_arith(N) rem 100000007.	
fib_arith(0)->0;
fib_arith(N) when N > 0 -> fib_arith(N, 0, 1).

fib_arith(0, F1, _F2) -> F1;
fib_arith(N, F1,  F2) -> fib_arith(N - 1, F2, F1 + F2).

fp-reverse-a-list.erl

%% https://www.hackerrank.com/challenges/fp-reverse-a-list/problem

% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).

main() ->
	solve().
solve()->
	Arr=get_array([]),
	print(Arr).

get_array(Acc)-> 
	Acc++
	case io:fread("", "~d") of
		{ok,[A]}->
			get_array(Acc)++[A];
		_->
			[]
	end.

print(Arr)-> 
	Fun=fun
		(X) ->
			io:format("~p~n",[X])
	end,
	lists:foreach(Fun,Arr).

jumping-bunnies.erl

%% https://www.hackerrank.com/challenges/jumping-bunnies/problem

% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).
-export([solve/2]).

main() ->
	 {ok, [Tc1]} = io:fread("", "~d"),
	 Pat= string:copies("~d ",Tc1),
	 {ok, [A|List]} = io:fread("", Pat),
	 io:format("~p~n",[solve(List,A)]).

mins(X,Y) when X<Y->
	{X,Y};
mins(X,Y)->
	{X,Y}.


gcd(X,0)->
	X;

gcd(X,Y)->
	gcd(Y,(X rem Y)).


lcm({X,Y})->
	X*Y div gcd(X,Y).

solve([],V)->
	V;
solve([B|Li],V)->
	solve(Li,lcm(mins(B,V))).

kmp-fp.erl

%% https://www.hackerrank.com/challenges/kmp-fp
% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).
-compile(export_all).
main() ->
	{ok,[Tc]}=io:fread("", "~d"),
	solve(Tc).
solve(Tc) when Tc =:=0->
	ok;
solve(Tc)->
	{ok,[Source,Find]}=io:fread("", "~s ~s"),
	io:format("~s~n",[test(Source, Find)]),
	solve(Tc-1).

 test(Source, Find) ->
    case find(Source, Find)of 
    	{not_found} -> 'NO';
    	_-> 'YES'
    end.


find(MWord,SWord) when is_list(MWord),is_list(SWord) ->
  search(MWord, SWord,1).
  
search(MWord,SWord,M) when M=<length(MWord)->
  case lists:nth(M, MWord) == lists:nth(1, SWord) of
	  true  -> 
		  case doSearch(MWord, SWord, M+1, 2) of 
			  {not_found} ->search(MWord, SWord, M+1);
			  Found -> {found}
		  end;
	  false -> search(MWord, SWord,M+1)
  end;

search(MWord,SWord,M) ->
	{not_found}.

doSearch(MWord,SWord,M,I) when I==length(SWord)+1 ->
	{found,M-I+1,I-1};

doSearch(MWord,SWord,M,I) when M>length(MWord) ->
   {not_found};

doSearch(MWord,SWord,M,I) ->
   case lists:nth(M, MWord)==lists:nth(I, SWord) of
        false -> {not_found};
        true -> doSearch(MWord, SWord, M+1, I+1)
   end.

lambda-march-compute-the-area-of-a-polygon.erl

%% https://www.hackerrank.com/challenges/lambda-march-compute-the-area-of-a-polygon/problem

% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).

main() ->
	 {ok, [Tcs]} = io:fread("", "~d"),
	 solve(Tcs).

solve(0)->
	ok;
solve(Tc)->
	Data=load(Tc,[]),
	F= fun(I,Acc) ->
		
		V=case I+1=:=length(Data)+1 of
			false->
				dis(lists:nth(I,Data),lists:nth(I+1,Data));
			true->
				dis(lists:nth(I,Data),lists:nth(1,Data))
			end,
		case I rem 2 of
			1->
				Acc+V;
			0->
				Acc+V
			end
		end,

		R= lists:foldl(F,0,lists:seq(1,length(Data))),
		io:format("~p",[abs(R)/2]).

load(0,Agg)->
	Agg;
load(T,Agg)->
	{ok, [A,B]} = io:fread("", "~d ~d"),
	load(T-1,Agg++[{A,B}]).


dis({X1,Y1},{X2,Y2})->
	X1*Y2-X2*Y1.

missing-numbers-fp.erl

%%https://www.hackerrank.com/challenges/missing-numbers-fp/problem
-module(solution).
-export([main/0]).
-compile(export_all).
main() ->
	{ok,[A]}=io:fread("", "~d"),
	Ar=scan_array([],A),
	{ok,[B]}=io:fread("", "~d"),
	Br=scan_array([],B),
	Res=scan(Ar,Br),
	print(Res).

scan_array([],N)->	
	Line=line_scan(N),
	{ok,A}=io:fread("", Line),
	A.

line_scan(1)->
	"~d";
line_scan(N)->
	"~d "++line_scan(N-1).

scan(A,B)->	
	Fun=fun(X,Acc)->
			{A1,Acc1}=Acc,
			case lists:member(X,A1)of
				true->	
					{
						lists:delete(X,A1),Acc1
					};
				false->	
					{
						A1,Acc1++[X]
					}
		end
	end,
	{_,L}=lists:foldl(Fun,{A,[]},B),
	L.
print([])->
	io:format("~n");
print(L) when length(L)==1 ->
	[H|List]=lists:usort(L),
	io:format("~p",[H]),
	print(List);
print(L)->
	[H|List]=lists:usort(L),
	io:format("~p ",[H]),
	print(List).

pascals-triangle.erl

%% https://www.hackerrank.com/challenges/pascals-triangle/problem

% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).

main() ->
	{ok,[A]}=io:fread("", "~d"),
	R=lists:reverse(pascal(A)),
	Fun=fun(X) ->
			print(X)
	end,
	lists:foreach(Fun,R).
 
pascal(1)-> [[1]];
pascal(N) ->
    L = pascal(N-1),
    [H|_] = L,
    [lists:zipwith(fun(X,Y)->X+Y end,[0]++H,H++[0])|L].


print(List)-> 
	[H|List1]=List,
	Fun=fun(X)->
		io:format(" ~p",[X])
	end,
	io:format("~p",[H]),
	lists:foreach(Fun,List1),
	io:format("~n").

pentagonal-numbers.erl

%%https://www.hackerrank.com/challenges/pentagonal-numbers/problem
% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).
-compile(export_all).
main() ->
	{ok,[A]}=io:fread("", "~d"),
	solve(A).

solve(N)->	
	{ok,A}=io:fread("",line_scan(N)),
	do_solve(A).

do_solve([])->
	ok;
do_solve(Arr)->	
	[H|List]=Arr,
	io:format("~p~n",[ans(H)]),
	do_solve(List).

scan_array([],N)->	
	Line=line_scan(N),
	{ok,A}=io:fread("", Line),
	A.

line_scan(1)->
	"~d";
line_scan(N)->
	"~d "++line_scan(N-1).


fib(N)->
	fib_arith(N) rem 100000007.	
fib_arith(0)->0;
fib_arith(N) when N > 0 -> fib_arith(N, 0, 1).

fib_arith(0, F1, _F2) -> F1;
fib_arith(N, F1,  F2) -> fib_arith(N - 1, F2, F1 + F2).

ans(N)->
	N*((3*N)-1)div 2.

remove-duplicates.erl

%%https://www.hackerrank.com/challenges/remove-duplicates/problem

% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).
-compile(export_all).
main() ->
	{ok,[A]}=io:fread("", "~s"),
	B=scanner(A),
	io:format("~s~n",[B]).
scanner(A)-> 
	Fun=fun(X,Acc)->
		case lists:member(X,Acc)of
			true-> 
				Acc;
			false-> 
				Acc++[X]
			end
	end,

	lists:foldl(Fun,[],A).

rotate-string.erl

%% https://www.hackerrank.com/challenges/rotate-string/problem
% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).
-compile(export_all).
main() ->
	{ok,[A]}=io:fread("", "~d"),
	scanner(A).
scanner(0)->
	ok;
scanner(N)->
	{ok,[A]}=io:fread("", "~s"),
	rotate(A),
	scanner(N-1).

rotate(List)->
	rotate(List,length(List)).
rotate(List,1)->
	[H|List1]=List,
	NewList=List1++[H],
	io:format("~s~n",[NewList]);

rotate(List,N)-> 
	[H|List1]=List,
	NewList=List1++[H],
	io:format("~s ",[NewList]),
	rotate(NewList,N-1).

string-mingling.erl

%% https://www.hackerrank.com/challenges/string-mingling

-module (solution).

-export ([main/0]).

main()->

	{ok,[A]}=io:fread("", "~s"),
	{ok,[B]}=io:fread("", "~s"),
	R=combine(A,B),
	io:format("~s~n",[R]).



combine(X,Y) when X =:= []; Y =:= [] -> []; 
combine([H1|A1],[H2|B1])->
	[H1,H2|combine(A1,B1)].

% solve(A,B)->

% 	lists:foldl(Fun,"",[A,B])

% zip3(X, Y) when X =:= []; Y =:= [] -> [];
% zip3([HX | TX], [HY | TY]) -> [ HX, HY| zip3(TX, TY)].

string-o-permute.erl

%% https://www.hackerrank.com/challenges/string-o-permute/problem

% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).

main() ->
	 {ok, [Tcs]} = io:fread("", "~d"),
	 solve(Tcs).

load(0,Agg)->
	Agg;
load(T,Agg)->
	{ok, [A]} = io:fread("", "~s"),
	load(T-1,Agg++[A]).

solve(0)->
	ok;
solve(Tc)->
	Data=load(Tc,[]),
	F= fun(I) ->
		E= ff(I,""),
		E1= lists:flatten(E),
		io:format("~s~n",[E1])
	end,	
	lists:foreach(F,Data).


ff([],Result)->
	Result;
ff([A,B],Result)->
	[Result,B,A];
ff([A,B|Word],Result)->
	ff(Word,[Result,B,A]).

string-reductions.erl

%% https://www.hackerrank.com/challenges/string-reductions/problem

% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

-module(solution).
-export([main/0]).
-compile(export_all).
main() ->
	{ok,[A]}=io:fread("", "~s"),
	B=scanner(A),
	io:format("~s~n",[B]).
scanner(A)-> 
	Fun=fun(X,Acc)->
		case lists:member(X,Acc)of
			true-> 
				Acc;
			false-> 
				Acc++[X]
			end
	end,

	lists:foldl(Fun,[],A).