Advent of Code 2016 Day 2
Part 1
- Setting up the data structures
- A double-
reduce()r to solve the puzzle
Setting up the data structures
My map for traversing the array based on the direction:
{
'U': [-1,0],
'R': [0,1],
'D': [1,0],
'L': [0,-1]
}
My data structure for the keypad:
[
[1,2,3],
[4,5,6],
[7,8,9]
]
5 is at [1,1]
A double-reduce()r to solve the puzzle
The iteration portion of my algorithm in pseudocode:
For each line from the input
Accumulate a code - starting as an empty string
For each character in the line
Accumulate a 2-element array of coordinates
If the next location is a valid cell
Return the coordinate of the next location
Else
Return the coordinate of the current location
Add the value at the final cell to the string
The iteration portion of my algorithm in JavaScript:
input.reduce(
(code, line) => {
key = line.reduce(
(coords, path) =>
keypad[coords[0] + map[path][0]] &&
keypad[coords[0] + map[path][0]][coords[1] + map[path][1]]
? [ coords[0] + map[path][0],
coords[1] + map[path][1] ]
: coords,
key.slice()
)
return code += keypad[key[0]][key[1]]
}, ""
)
Part 1: solved!
Part 2
Three updates and done!
Update 1: Expand the data structure
My data structure for the keypad:
[
[0, 0, 1, 0, 0],
[0, 2, 3, 4, 0],
[5, 6, 7, 8, 9],
[0, 'A','B','C', 0],
[0, 0, 'D', 0, 0]
]
Update 2: Adjust the starting location
5 is at [2,0] now
Update 3: Add a clause to the array-cell-checking condition - checking for a value of 0
The iteration portion of my algorithm in JavaScript:
input.reduce(
(code, line) => {
key = line.reduce(
(coords, path) =>
keypad[coords[0] + map[path][0]] &&
keypad[coords[0] + map[path][0]][coords[1] + map[path][1]] &&
keypad[coords[0] + map[path][0]][coords[1] + map[path][1]] !== 0
? [ coords[0] + map[path][0],
coords[1] + map[path][1] ]
: coords,
key.slice()
)
return code += keypad[key[0]][key[1]]
}, ""
)
Part 2: solved!
I did it!!
- I solved both parts!
- Using nested
reduce()s again! - And using my tried and true array traversing techniques!
Bring on Day 1...and hopefully a strong end to an overall fun and relatively fast-solved year!
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