better constrain possible problems

It seems the cleanest way to get what we want is to generate the
solution up front.

0017-on.keychord_press

@@ -4,8 +4,6 @@ print(chord)
 		new()
 	elseif chord == '`' then
 		if Draw == 'problem' then
-			Draw = 'char'
-		elseif Draw == 'char' then
 			Draw = 'solution'
 		elseif Draw == 'solution' then
 			Draw = 'problem'

0018-Char

@@ -1,9 +0,0 @@
--- a set of numbers that uniquely characterizes a sum-grid instance.
-Char = {
-	row_totals={0, 0},
-	col_totals={0, 0},
-	data={
-		{0, 0},
-		{0, 0},
-	},
-}

0019-Solution

@@ -1,4 +1,3 @@
--- solution for the sum-grid problem defined by Char.
 Solution = {
 	row_totals={0, 0},
 	col_totals={0, 0},

0020-solve

@@ -1,21 +0,0 @@
-solve = function()
-	print('solve')
-	-- copy the slots we have
-	local c = Char.col_totals
-	local d = Char.data
-	Solution = {
-		col_totals = {c[1], c[2]},
-		data = {
-			{d[1][1], d[1][2] },
-			{ },
-		}
-	}
-	-- fill out the remaining data
-	Solution.data[2][1] = c[1] - d[1][1]
-	Solution.data[2][2] = c[2] - d[1][2]
-	d = Solution.data
-	Solution.row_totals = {
-		d[1][1] + d[1][2],
-		d[2][1] + d[2][2],
-	}
-end

0021-Draw

@@ -1 +1 @@
-Draw = 'problem'
+Draw = 'problem'  -- or 'solution'

0024-generate

@@ -1,14 +1,20 @@
 generate = function()
-	-- a sum grid is fully characterized by 4 numbers
-	Char = {
+	local g = {
+		col_totals = {'', ''},
+		row_totals = {'', ''},
 		data = {
-			{ math.random(1,9), math.random(1,9) },
-			{ '', ''},
+			{'', ''},
+			{'', ''},
 		},
-		row_totals = { '', '' },
-	}
-	Char.col_totals = {
-		math.random(Char.data[1][1]+1,10),
-		math.random(Char.data[1][2]+1,10)
 	}
+	g.data[1][1] = math.random(1,9)
+	local d11 = g.data[1][1]
+	g.row_totals[1] = math.random(d11+1,10)
+	g.col_totals[1] = math.random(d11+1,10)
+	g.data[1][2] = g.row_totals[1] - d11
+	g.data[2][1] = g.col_totals[1]-d11
+	g.row_totals[2] = math.random(g.data[1][2]+1,10)
+	g.col_totals[2] = math.random(g.data[2][1]+1,10)
+	g.data[2][2] = g.col_totals[2]-g.data[2][1]
+	Solution = g
 end

0027-new

@@ -1,5 +1,4 @@
 new = function()
 	generate()
-	solve()
 	create_problem()
 end