口算20以内加

ADD_X_RANGE = (1..20)		#第一个加数的范围
ADD_Y_RANGE = (1..20)		#第二个加数的范围
ADD_RES_MAX = 20			#加法和最大值
ADD_RES_MIN = 10			#加法和最小值
ADD_FORMULA_CNTS = 100		#算式总的个数
LINE_CNTS = 5				#每行算式个数

res = {}
while res.size < ADD_FORMULA_CNTS do
	x =  rand(ADD_X_RANGE)
	y =  rand(ADD_Y_RANGE)
	if (x+y) <= ADD_RES_MAX && (x+y) > ADD_RES_MIN
		key = sprintf("%d+%d", x, y)
		str = sprintf("%-2d + %-2d =     ", x, y)
		res[key] = str
	end 
end



line  = 0
res.each{|x,y|
	printf(y)
	line = line + 1
	if line == LINE_CNTS
		puts ""
		puts ""
		line = 0
	end
}