Talk is cheap,show me the code~

窮舉法

計算次數 3^8 = 6561,輸出等於100的結果

arr = {1,2,3,4,5,6,7,8,9}
flag = {"+","-",""}
function generateStr(arr,str,index) 
    if index > #arr then
        if loadstring("return " .. str )() == 100 then
            print(str .. "=100")
        end     
    else
        for
 
 i = 1, #flag do 
             generateStr(arr,str .. flag[i] ..arr[index],index + 1) 
        end
    end
end

generateStr(arr,arr[1],2)

1+2+3-4+5+6+78+9=100
1+2+34-5+67-8+9=100
1+23-4+5+6+78-9=100
1+23-4+56+7+8+9=100
12+3+4+5-6-7+89=100
12+3-4+5+67+8+9=100
12-3-4+5-6+7+89=100
123+4-5+67-89=100
123+45-67+8-9=100
123-4-5-6-7+8-9=100
123-45-67+89=100