day 13: cleaned up a bit

12023/13/13.lua

@@ -1,28 +1,19 @@
 io.input("input")
 
-rows = {}
-cols = {}
-len = 0
-ngroup = 1
 sum1 = 0
 sum2 = 0
 
+function hex(n) return string.format("%04x",n) end
+
 function reset()
+    len = 0
     r = 0
     vindexes = {}
     hindexes = {}
     rows = {}
+    cols = {}
 end
 
-function difference(a,b) --string based
-    local diffs = {}
-    for i=1,#a do
-        if a:sub(i,i)~=b:sub(i,i) then 
-            table.insert(diffs,i)
-        end
-    end
-    return diffs
-end
 function one_difference(a,b) --numeric
     local diff = a~b
     -- is power of 2?
@@ -45,7 +36,6 @@ end
 
 function new_reflection(nums,N,ignore)
     local vdiff = list_of_one_diff(nums)
-    local result = nil
     for _, d in ipairs(vdiff) do
         local i,j,diff = table.unpack(d)
         local newnums = {}
@@ -54,7 +44,7 @@ function new_reflection(nums,N,ignore)
         local newvalue = newnums[j]
         newnums[i] = newvalue
 
-        print(i,j,string.format("%04x",diff),string.format("%04x",nums[i]),string.format("%04x",nums[j]),string.format("%04x",newvalue))
+        --print(i,j,hex(diff),hex(nums[i]),hex(nums[j]),hex(newvalue))
 
         -- calculate new indexes
         local indexes = {}
@@ -66,15 +56,13 @@ function new_reflection(nums,N,ignore)
 
         print("attempt reflection")
         local r = reflection(indexes, newnums, N,ignore)
-        if r then result = r end
+        if r then return r end
     end
-    return result 
+    return nil
 end
 
 function two_consecutives(t)
     if #t==1 then return nil
-    elseif #t==2 then
-        if t[1]+1==t[2] then return {table.pack(t[1], t[2])} end
     else
         local consecutives = {}
         for i=1,#t-1 do
@@ -89,11 +77,9 @@ end
 
 function reflection(indexes, nums, N, ignore)
     print(N)
-    local result = nil
     local consecutives = {}
     for num, ix in pairs(indexes) do
-        print(string.format("%04x",num), table.concat(ix,","))
-        if #ix==4 then print("HERE") end
+        print(hex(num), table.concat(ix,","))
         local cs = two_consecutives(ix)
         if cs then
             for _, c in ipairs(cs) do
@@ -101,27 +87,27 @@ function reflection(indexes, nums, N, ignore)
             end
         end
     end
-    print("consecutives")
     if #consecutives>0 then
+        print("list of consecutives")
         for _, c in ipairs(consecutives) do
             local a,b = table.unpack(c)
+            if a==ignore then goto continue end
             local x,y = a,b
             print(a,b)
             local reflected = true
             while reflected and x>=1 and y<=N do
-                print("testing",x,y,nums[x],nums[y])
+                print("testing",x,y,hex(nums[x]),hex(nums[y]))
                 if nums[x]~=nums[y] then 
                     reflected = false
                 end
                 x,y = x-1, y+1
             end
             print(reflected, a)
-            if reflected and (not ignore or ignore~=a)then 
-                result = a
-            end
+            if reflected then return a end
+            ::continue::
         end
     end
-    return result
+    return nil
 end
 
 function end_of_group()
@@ -133,14 +119,15 @@ function end_of_group()
 
     print("vindexes")
     local vr = reflection(vindexes, cols, len)
+    if vr then
+        print("VR",vr)
+        sum1 = sum1 + vr
+    end
 
     print("hindexes")
     local hr = reflection(hindexes, rows, r)
-
-    if vr then
-        sum1 = sum1 + vr
-    end
     if hr then
+        print("HR",hr)
         sum1 = sum1 + 100*hr
     end
 
@@ -150,24 +137,16 @@ function end_of_group()
     local nvr = new_reflection(cols, len, vr)
     if nvr then
         print("NVR",nvr)
+        sum2 = sum2 + nvr
     end
 
     print("hdifferences")
     local nhr = new_reflection(rows, r, hr)
     if nhr then
         print("NHR",nhr)
-    end
-
-    if nvr then
-        sum2 = sum2 + nvr
-    end
-    if nhr then
         sum2 = sum2 + 100*nhr
     end
 
-    --table.move(vdiff,1,#vdiff,1,tdiff)
-
-    ngroup = ngroup + 1
     -- reset
     reset()
     print()
@@ -178,26 +157,20 @@ for line in io.lines() do
     if line:find("[%#%.]") then
         if r==0 then
             len = #line
---            for i=1,len do cols[i]="" end
             for i=1,len do cols[i]=0 end
-            print("G",ngroup)
         end
         print(line)
         r = r+1
-        --local hnum = line
         local hnum = 0
         for i=1,len do
             local char = line:sub(i,i)
-            --cols[i] = cols[i] .. char
             local bit = char=="#" and 1 or 0
             hnum = (hnum<<1) | bit
             cols[i] = (cols[i]<<1) | bit
-
         end
         table.insert(rows, hnum)
         if not hindexes[hnum] then hindexes[hnum]={} end
         table.insert(hindexes[hnum],r)
-        --print(r,line,hnum)
     else
         end_of_group()
     end