The mayor of the colorful world of Blocktopia has asked Bob the Builder to design $N-1$ buildings.
All buildings in Blocktopia are built from square blocks of various colors.
A building of height $H$ can be seen as $H$ blocks stacked on top of each other.
He has also requested some strange requirements on the design of the buildings:
- Every building must have the same height $H$.
- Each building must be bicolored: it must use exactly 2 different colors of blocks.
- Maximize the height $H$.
Bob has $N$ different colors of blocks, in which he has $A[i]$ blocks of the $i$-th color.
Bob may be an expert at construction, but he is no master at colors!
Can you help Bob determine the maximum height $H$ and provide a valid construction of the $N-1$ buildings?
Figure 1 | Illustrated by Sunny
As an example, this is a valid design of buildings.
Figure 2 | Illustrated by Sunny
As an example, this is an invalid design of buildings.
Input
The first line contains a single integer $N$.
The next line contains $N$ integers, where the $i$-th integer is $A[i]$.
Output
Output the maximum height $H$ on the first line.
Then output $N-1$ lines describing each building with four integers: $i, x, j, y$:
$i$ and $j$ denote the two colours that the building is made out of; and
$x$ and $y$ denote the number of blocks used which are colors $i$ and $j$ respectively.
The outputted numbers should satisfy the following:
- $1\le i, j \le N$
- $i\neq j$
- $x+y=H$
If there are multiple solutions, output any of them. It is guaranteed that a solution exists under the given costraints.
Constraints
For all subtasks:- $2 \le N \le 5\times 10^5$
- $2 \le A[i] \le 10^9$
Subtask 1 (15%): $N=3$
Subtask 2 (20%): All $A[i]$ are equal
Subtask 3 (40%): $N\le 10^3$
Subtask 4 (25%): No additional constraints
Sample Test Cases
Input | Output | |
---|---|---|
3 2 2 3 |
3 1 2 2 1 2 1 3 2 |
Scoring: Per Subtask
Authored by s19x17
Appeared in 2023 Mini Contest 5 (JSOI Selection)