NOI '20 P4 - Dish
View as PDFThe chef is preparing  dishes, and each dish uses 
 grams of
ingredients. As a result, the chef has bought 
 ingredients, and the
ingredients are numbered 
. The 
-th ingredient weighs
 grams. The sum of weights of all 
 ingredients is exactly
 grams. 
 and 
 are positive integers.
An ingredient may be used in multiple dishes. However, each dish may use
at most 2 ingredients. Now you are asked to decide if there exists a
valid way to prepare the  dishes. More formally, the final plan shall
satisfy the following requirements:
Prepare
dishes in total.
Each dish uses at most 2 ingredients.
Each dish uses exactly
grams of ingredients.
For each ingredient used in a given dish, the amount used is a positive integer measured in grams.
All of the
ingredients will be completely utilized.
If there exists a feasible solution, you should output a detailed plan.
Input Specification
In this problem, each test case may have multiple instances.
The first line is an integer  denoting the number of instances. For
each instance, the first line contains three positive integers 
denoting the number of ingredients, the number of dishes to prepare, and
the amount of ingredients each dish uses. The second line contains 
integers, and the 
-th integer denotes there are 
 grams of
ingredient 
.
Output Specification
For each instance, if there is no feasible solution, output -1.
Otherwise, you need to output  lines, and each line specifies the
way to prepare a dish. Depending on the number of ingredients used in
the dish, a line shall be in one of the following two formats:
- a line containing two integers 
and
denoting the dish will use
grams of ingredient
. Here,
and
.
 - a line containing four integers 
denoting the dish will use
grams of ingredient
and
grams of ingredient
. Here,
,
,
,
.
 
Your answer will be checked by a special judge. Therefore, if there are multiple feasible solutions, you may print any solution. You should make sure the output is in the correct format, and two adjacent integers in a line are separated by a single space. Finally, your output shall not contain any extra characters.
Sample Input
4
1 1 10
10
4 3 100
80 30 90 100
5 3 1000
200 400 500 900 1000
6 4 100
25 30 50 80 95 120
Sample Output
1 10
1 80 2 20
2 10 3 90
4 100
-1
1 5 5 95
1 20 4 80
2 30 6 70
3 50 6 50
For all test cases:
, 
, 
, 
,
, 
.
| Test case | |||
|---|---|---|---|
| 1~3 | |||
| 4~5 | |||
| 6~7 | |||
| 8~9 | |||
| 10 | |||
| 11~12 | |||
| 13~14 | |||
| 15~17 | |||
| 18~20 | 
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