Initial data commit

Task/Move-to-front-algorithm/FreeBASIC/move-to-front-algorithm.basic

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+#define FAIL -1
+
+sub mtf( s() as string, i as uinteger )
+    'moves the symbol at index i to the front and shifts preceding ones back
+    dim as string*1 t = s(i)
+    for j as uinteger = i to 1 step -1
+        s(j) = s(j-1)
+    next j
+    s(0)=t
+end sub
+
+sub make_symbols( s() as string )
+    'populates an array of strings with the lowercase alphabet
+    for i as uinteger = 97 to 122
+        s(i-97) = chr(i)
+    next i
+end sub
+
+function find( s() as string, l as string ) as integer
+    'returns the index of the first occurrence of the symbol l in s()
+    for i as uinteger = 0 to ubound(s)
+        if s(i) = l then return i
+    next i
+    return FAIL
+end function
+
+sub encode( s() as string, ind() as uinteger )
+    dim as integer n = ubound(s), i
+    redim as uinteger ind(0 to n)
+    dim as string a(0 to 25)
+    make_symbols(a())
+    for z as uinteger = 0 to n
+        i = find( a(), s(z) )
+        if i = FAIL then
+            print "Uh oh! Couldn't find ";s(z);" in alphabet."
+            end
+        end if
+        mtf( a(), i )
+        ind(z) = i
+    next z
+end sub
+
+sub decode( s() as string, ind() as uinteger )
+    dim as integer n = ubound(ind), i
+    redim as string s(0 to n)
+    dim as string a(0 to 25)
+    make_symbols(a())
+    for z as uinteger = 0 to n
+        s(z) = a(ind(z))
+        mtf(a(), ind(z))
+    next z
+end sub
+
+sub printarr( s() as string )
+    for i as uinteger = 0 to ubound(s)
+        print s(i);
+    next i
+    print
+end sub
+
+sub printind( ind() as integer )
+    for i as uinteger = 0 to ubound(ind)
+        print ind(i);" ";
+    next i
+    print
+end sub
+
+sub compose( s() as string, b as string )
+    'turns a string into a zero-indexed array of single letters
+    'The reason we use such arrays is to get them zero-indexed
+    'and to make the point that we could work with multi-char
+    'symbol tables if we wanted to
+    dim as integer n = len(b), i
+    redim as string s(0 to n-1)
+    for i = 0 to n-1
+        s(i) = mid(b, 1+i, 1)
+    next i
+end sub
+
+'-----------now the tests-------------
+redim as string s(0)
+redim as integer ind(0)
+
+compose( s(), "broood" )
+encode( s(), ind() )
+printind( ind() )
+decode( s(), ind() )
+printarr( s() ) : print
+
+compose( s(), "bananaaa" )
+encode( s(), ind() )
+printind( ind() )
+decode( s(), ind() )
+printarr( s() ) : print
+
+compose( s(), "hiphophiphop" )
+encode( s(), ind() )
+printind( ind() )
+decode( s(), ind() )
+printarr( s() )