clear;


target="METHINKS IT LOOKS LIKE A WEASEL"
n=length(target)


#FUNCTION TO CALCULATE HOW CLOSE A STRING IS TO THE TARGET
function pt=points(off)
	target="METHINKS IT LOOKS LIKE A WEASEL";
	n=length(target);
	
	pt=0;
	for i=1:n
		if (off(i)==target(i))
			pt=pt+1;	# INCRASE POINTS IF THERE ARE IDENTICAL LETTERS AT IDENTICAL POSITIONS
		endif
	endfor
endfunction

#FUNCTION TO MUTATE A STRING sh INTO A STRING st BY CHANGING m RANDOMLY CHOSEN CHARACTERS IN THE ORIGINAL TO m OTHER RANDOMLY CHOSEN ONES
function st=mutate(sh,m)
	for i=1:m
		r=round(rand*(length(sh)-1))+1;
		off=round(rand*26)+64;
		if (off==64)
			sh(r)=char(32);		
		else 
			sh(r)=char(off);
		endif
	endfor
	st=sh;		
endfunction


# NOTE THE START TIME
startt=time;


# Generate a random string of n characters - THE ANCESTOR STRING

for i=1:n
	parentN=round(rand*26)+64;
	if (parentN!=64)
		ancestor(i)=char(parentN);
	else 
		ancestor(i)=char(32);
	endif
endfor

ancestor	# SHOW THE ANCESTOR STRING ON SCREEN

G=1;		# INITIATE THE GENERATION COUNTER				
o=5;		# LET THE ANCESTOR BE SO FERTILE AS TO GENERATE 5 OFFSPRING IN ITS LIFETIME

parent=ancestor;	# PARENT STORES THE SELECTED INDIVIDUAL (A STRING) WHICH PRODUCES 'o' OFFSPRING IN ITS LIFETIME 

while (strcmp(parent,target)==0)	# STOP WHEN THE SELECTED INDIVIDUAL IS EXACTLY THE TARGET STRING

	for i=1:o
		offs(i,:)=mutate(parent,1);	# PRODUCE 'o' OFFSPRING FROM THE PARENT WITH MINIMAL MUTATION AND CALCULATE HOW CLOSE EACH
		p(i)=points(offs(i,:));		# IS TO THE TARGET STRING (Note that duplicating with an error greater than one decreases the rate
						# of convergence significantly. Keep mutation to a minimum (1) for best results)
	endfor
	
	G=G+1;			# INCREMENT GENERATION COUNTER
		
	[mx,mxp]=max(p);	# FIND WHICH OFFSPRING SCORED THE MAXIMUM POINTS
	parent=offs(mxp,:)	# SET THAT OFFSPRING TO BE THE PARENT FOR THE NEXT GENERATION
	o=mx+5			# INCREASE THAT OFFSPRING'S REPRODUCTION RATE SINCE IT IS CLOSER TO THE TARGET (OPTIONAL).
				# AS AN ALTERNATIVE, SET o=20 or some higher value and remove the previous line

endwhile

G		# SHOW NUMBER OF GENERATIONS PASSED
parent		# THIS WILL BE THE SAME AS THE TARGET STRING NOW


endt=time;
time=endt-startt	# SHOW HOW MUCH TIME PASSED