diff --git a/data/day_14.txt b/data/day_14.txt
new file mode 100644
index 0000000..7810707
--- /dev/null
+++ b/data/day_14.txt
@@ -0,0 +1,102 @@
+HHKONSOSONSVOFCSCNBC
+
+OO -> N
+VK -> B
+KS -> N
+PK -> H
+FB -> H
+BF -> S
+BB -> V
+KO -> N
+SP -> K
+HK -> O
+PV -> K
+BP -> O
+VO -> V
+OP -> C
+BS -> V
+OK -> V
+KN -> H
+KC -> N
+PP -> F
+NB -> V
+CH -> V
+HO -> K
+PN -> H
+SS -> O
+CK -> P
+VV -> K
+FN -> O
+BH -> B
+SC -> B
+HH -> P
+FO -> O
+CC -> H
+OS -> H
+FP -> S
+HC -> F
+BO -> F
+CF -> S
+NC -> S
+HS -> V
+KF -> O
+ON -> C
+CN -> K
+VF -> F
+NO -> K
+CP -> N
+HF -> K
+CV -> N
+HN -> K
+VH -> B
+KK -> P
+CS -> O
+VS -> P
+NH -> F
+CB -> S
+BV -> P
+FK -> F
+NV -> O
+OV -> K
+SB -> N
+NF -> O
+VN -> S
+OH -> O
+PS -> N
+HB -> H
+SV -> V
+CO -> H
+SO -> P
+FV -> N
+PF -> O
+NN -> S
+KB -> P
+NP -> F
+OC -> S
+FS -> P
+FH -> P
+VP -> K
+BN -> O
+NS -> H
+VB -> V
+PO -> K
+KP -> N
+SN -> O
+BC -> H
+SF -> V
+PC -> O
+NK -> F
+BK -> V
+KH -> S
+SH -> S
+SK -> H
+OB -> V
+PH -> N
+PB -> C
+HV -> N
+HP -> V
+FF -> B
+OF -> P
+VC -> S
+KV -> C
+FC -> F
diff --git a/data/day_15.txt b/data/day_15.txt
new file mode 100644
index 0000000..15a36f8
--- /dev/null
+++ b/data/day_15.txt
@@ -0,0 +1,100 @@
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diff --git a/src/day_14.jl b/src/day_14.jl
new file mode 100644
index 0000000..7b4ee16
--- /dev/null
+++ b/src/day_14.jl
@@ -0,0 +1,58 @@
+include(joinpath(readchomp(`git rev-parse --show-toplevel`), "aoc.jl"))
+import .Aoc: @aoc
+using Pipe: @pipe
+
+function sliding(in, w::Int64; step::Int = 1)
+	((@view in[i:i+w-1]) for i in 1:step:length(in)-w+1)
+end
+
+function prep_input(input)
+	pairs = Dict()
+	for pair in sliding(input[1], 2)
+		!haskey(pairs, pair) ? (pairs[pair] = 0) : nothing
+		pairs[pair] += 1
+	end
+
+	dict = Dict()
+	for l in input[3:end]
+		p, t = split(l, " -> ")
+		dict[p] = (p[1] * t, t * p[2])
+	end
+	return (pairs, dict)
+end
+
+function step(pairs, dict)
+	new = Dict()
+	for pair in keys(pairs)
+		p1, p2 = dict[pair]
+		new[p1] = get(new, p1, 0) + pairs[pair]
+		new[p2] = get(new, p2, 0) + pairs[pair]
+	end
+	return new
+end
+
+function solve(pairs, dict, rounds, last)
+	for _ in 1:rounds
+		pairs = step(pairs, dict)
+	end
+
+	c = Dict()
+	for p in keys(pairs)
+		!haskey(c, p[1]) ? (c[p[1]] = 0) : nothing
+		c[p[1]] += pairs[p]
+	end
+	c[last] += 1 # add one more count for last character in polymer
+	return maximum(values(c)) - minimum(values(c))
+end
+
+function p1(input::Vector{String})
+	pairs, dict = prep_input(input)
+	return solve(pairs, dict, 10, input[begin][end])
+end
+
+function p2(input::Vector{String})
+	pairs, dict = prep_input(input)
+	return solve(pairs, dict, 40, input[begin][end])
+end
+
+@aoc(2021, 14)
diff --git a/src/day_15.jl b/src/day_15.jl
new file mode 100644
index 0000000..2fe69fb
--- /dev/null
+++ b/src/day_15.jl
@@ -0,0 +1,47 @@
+include(joinpath(readchomp(`git rev-parse --show-toplevel`), "aoc.jl"))
+import .Aoc: @aoc
+using Pipe: @pipe
+using Graphs, SimpleWeightedGraphs
+
+function prep_input(input)
+	[ parse.(Int, collect(l)) for l in input ]
+end
+
+function lowest_cost(grid)
+	q = [(1,1,0)]
+	costs = Dict()
+	while true
+		x,y,c = popfirst!(q)
+		x == length(grid) && y == length(grid[1]) ? (return c) : nothing
+		for (x2, y2) in [(x+1,y),(x-1,y),(x,y-1),(x,y+1)]
+			if x2 in 1:length(grid) && y2 in 1:length(grid[1])
+				cost = c + grid[x2][y2]
+				(x2, y2) in keys(costs) && costs[(x2, y2)] <= cost ? (continue) : nothing
+				costs[(x2, y2)] = cost
+				push!(q, (x2, y2, cost))
+			end
+		end
+		sort!(q)
+	end
+end
+
+function p1(input::Vector{String})
+	grid = prep_input(input)
+	return lowest_cost(grid)
+end
+
+function p2(input::Vector{String})
+	grid = prep_input(input)
+	newgrid = [ zeros(Int, 5*length(grid[1])) for _ in 1:5*length(grid) ]
+
+	for x in 1:length(newgrid), y in 1:length(newgrid[1])
+		v = grid[x%length(grid)+1][y%length(grid[1])+1]
+		for _ in 1:((x-1) ÷ length(grid) + (y-1) ÷ length(grid[1])) # ÷ performs integer division
+			v + 1 == 10 ? (v = 1) : (v += 1)
+		end
+		newgrid[x][y] = v
+	end
+	return lowest_cost(newgrid)
+end
+
+@aoc(2021, 15)