function [ codeword ] = huffman_encode( p )

n=length(p);
codeword=cell(1,n);
X=zeros(n,n);
temp=p;
%%
%Building the relationship matrix X.This matrix has all elements zero
%except for few entries which are substituted with 10 or 11.Number 10 denotes this
%entry is the minimum in the column and 11 indicates this is the second
%minimum.the minimum is replaced by 100 and second minimum is replaced by
%sum of the minimum and the second minimum.And processing for the next
%column progresses
for i=1:n-1
    [~ ,l]=sort(temp);
    X(l(1),i)=10;
    X(l(2),i)=11;
    temp(l(2))=temp(l(2))+temp(l(1));
    temp(l(1))=100;
end

i=n-1;
rows=find(X(:,i)==10);
codeword(rows)=strcat(codeword(rows),'1');
rows=find(X(:,i)==11);
codeword(rows)=strcat(codeword(rows),'0');
for i=n-2:-1:1
    row11=find(X(:,i)==11);
    row10=find(X(:,i)==10);
    codeword(row10)=strcat(codeword(row11),'1');
    codeword(row11)=strcat(codeword(row11),'0');
end
end


function [symbols,probability] = char_hist(message)

symbols=[];
probability=[];
n=length(message);
i=1;
while ~isempty(message)
    [mode_char,no_occurrances]=mode(message);
    symbols(i)=mode_char;
    probability(i)=no_occurrances;
    indices=find(message==mode_char);
    message(indices)='';
    i=i+1;
end
probability=probability/n;
end


function [msg] = huffman_decode(symb,code,bitstream)
%Assuming code to be in cell format
%n is the number of messages
% maxlen is maximum length of code
%Idea is simple.We are going to search for matching of bits until we reach
%maximum length of the codeword or match is found.When a match between bit
%or group of bits is found we notedown the corresponding symbol of the
%group of bits.
n=length(symb);
lengths=[];
for i=1:n
    len=length(char(code(i)));
    lengths=[lengths len];
end
maxlen=max(lengths);
msg='';
%bitstream length is denoted by streamlen
streamlen=length(bitstream);
i=1;
while i<=streamlen
    j=0;
    while j<maxlen
        c=bitstream(i:i+j);
        ind=1;
        while (ind<=n && ~isequal(char(code(ind)),c))
            ind=ind+1;
        end
        if ind<=n
            msg=[msg char(symb(ind))];
            break
        else j=j+1;
        end
    end
    i=i+j+1;
end


function [message] = read_file(filename)
fileId=fopen(filename,'r');
message=fscanf(fileId,'%c');
fclose(fileId);
end