• 74

## Learning Opportunities

This puzzle can be solved using the following concepts. Practice using these concepts and improve your skills.

## Goal

In a typical match-3 game, the goal is to create alignments of 3 or more identical tokens by swapping two adjacent tokens.

Your program must implement a hint system for a match-3 game by listing all pairs of tokens that could be swapped to generate horizontal or vertical alignements of 3 or more tokens within a 2D grid of 9 rows by 9 columns.

The pairs must be given ordered by row, then colum, i.e. from top left to bottom right.
A given pair must be given only once, i.e. if you report (A,B) you must not report (B,A) as well.
For instance, if the token at row 5 and column 7 can be swapped with each of its four neighbors, then the expected report is
4 7 5 7
5 6 5 7
5 7 5 8
5 7 6 7
Input
9 lines: 9 integers, separated by spaces. Each value represents a given kind of token.
Output
Line 1: N, the number of pairs
N next lines: one pair expressed as 4 space-separated integers representing the row and column of swappable pairs, i.e. row1 col1 row2 col2
Constraints
Example
Input
```4 4 1 5 1 2 5 5 1
1 4 2 1 1 2 2 4 5
1 1 5 4 5 4 4 5 1
3 2 1 3 1 3 3 1 2
1 5 3 3 5 5 2 5 2
1 1 5 5 3 5 2 3 1
2 2 5 5 4 4 3 1 3
1 4 4 3 4 1 5 5 4
3 4 1 5 5 4 1 2 5```
Output
```26
0 2 1 2
0 3 1 3
0 8 1 8
1 7 1 8
1 7 2 7
2 0 3 0
2 2 3 2
2 3 2 4
2 4 3 4
3 0 4 0
3 3 3 4
4 1 4 2
4 1 5 1
4 3 4 4
4 3 5 3
4 4 5 4
4 6 4 7
5 3 5 4
5 4 5 5
5 7 6 7
6 0 7 0
7 3 7 4
7 3 8 3
7 4 7 5
7 8 8 8
8 4 8 5```

A higher resolution is required to access the IDE