solve day 9 parts 1 & 2

DATA/2023/example_input_day09.txt

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+0 3 6 9 12 15
+1 3 6 10 15 21
+10 13 16 21 30 45

SOLUTIONS/2023/Day_09.qmd

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+---
+title: "Day 9"
+author: "Julia Romanowska"
+jupyter: julia-1.9
+---
+
+```{julia}
+#| label: setup
+#| include: false
+using Markdown;
+```
+
+## The input
+
+Sequences of numbers.
+
+```{julia}
+#| label: read_data
+root = dirname(@__FILE__);
+input_file = joinpath(root, "..", "..", "DATA", "2023", "input_day09.txt");
+#input_file = joinpath(root, "..", "..", "DATA", "2023", "example_input_day09.txt");
+input_data = read(open(input_file, "r"), String);
+```
+
+```{julia}
+input_data = split(input_data, "\n") |>
+    x -> split.(x, " ");
+input_data = broadcast(x -> parse.(Int64, x), input_data[1:(end - 1)])
+```
+
+## Part 1
+
+### The problem and solution
+
+Gather all the last differences and extrapolate another number in each sequence.
+
+```{julia}
+next_num_in_seq = Int64[];
+for cur_seq in input_data
+    last_differences = Int64[];
+
+    cur_diff = diff(cur_seq);
+    while !all(cur_diff .== 0)
+        push!(last_differences, cur_diff[end]);
+        cur_diff = diff(cur_diff);
+    end
+
+    push!(last_differences, cur_seq[end]);
+    next_diff = 0;
+    for i in last_differences
+        next_diff += i;
+    end
+    push!(next_num_in_seq, next_diff);
+end
+```
+
+```{julia}
+#| echo: false
+Markdown.parse("""
+The sum of the extrapolated values is: $(sum(next_num_in_seq)).
+""")
+```
+
+
+# Part 2
+
+### The problem and solution
+
+Gather all the first differences and extrapolate previous number in each sequence.
+
+```{julia}
+prev_num_in_seq = Int64[];
+for cur_seq in input_data
+    first_differences = Int64[];
+
+    cur_diff = diff(cur_seq);
+    while !all(cur_diff .== 0)
+        push!(first_differences, cur_diff[begin]);
+        cur_diff = diff(cur_diff);
+    end
+
+    first_differences = first_differences[end:-1:1];
+    push!(first_differences, cur_seq[begin]);
+    prev_diff = 0;
+    for i in first_differences
+        prev_diff = i - prev_diff;
+    end
+    push!(prev_num_in_seq, prev_diff);
+end
+```
+
+```{julia}
+#| echo: false
+Markdown.parse("""
+The sum of the extrapolated values is: $(sum(prev_num_in_seq)).
+""")
+```
+

_freeze/SOLUTIONS/2023/Day_09/execute-results/html.json

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+{
+  "hash": "65d80f1ae3e11dfdbaa427cbeb703687",
+  "result": {
+    "markdown": "---\ntitle: Day 9\nauthor: Julia Romanowska\n---\n\n\n## The input\n\nSequences of numbers.\n\n::: {#read_data .cell execution_count=2}\n``` {.julia .cell-code}\nroot = dirname(@__FILE__);\ninput_file = joinpath(root, \"..\", \"..\", \"DATA\", \"2023\", \"input_day09.txt\");\n#input_file = joinpath(root, \"..\", \"..\", \"DATA\", \"2023\", \"example_input_day09.txt\");\ninput_data = read(open(input_file, \"r\"), String);\n```\n:::\n\n\n::: {.cell execution_count=3}\n``` {.julia .cell-code}\ninput_data = split(input_data, \"\\n\") |>\n    x -> split.(x, \" \");\ninput_data = broadcast(x -> parse.(Int64, x), input_data[1:(end - 1)])\n```\n\n::: {.cell-output .cell-output-display execution_count=4}\n```\n200-element Vector{Vector{Int64}}:\n [8, 7, 3, 3, 21, 91, 297, 830, 2098, 4940  …  23745, 49682, 102071, 207392, 418543, 839856, 1672689, 3294947, 6393907, 12179007]\n [14, 16, 21, 48, 126, 306, 696, 1534, 3320, 7031  …  28549, 54126, 98307, 171187, 286281, 460690, 714762, 1070999, 1551934, 2176694]\n [16, 25, 28, 16, -15, -58, -95, -93, 27, 484  …  5395, 13786, 31983, 68678, 138244, 263370, 478515, 834334, 1403242, 2286295]\n [11, 14, 21, 40, 76, 125, 170, 186, 176, 285  …  4181, 13601, 38634, 99880, 241509, 555257, 1225456, 2610109, 5381286, 10759714]\n [14, 22, 47, 116, 268, 548, 997, 1638, 2458, 3386  …  4832, 4664, 3160, -511, -7454, -19098, -37250, -64153, -102548, -155740]\n [16, 17, 29, 64, 133, 246, 412, 639, 934, 1303  …  2282, 2899, 3604, 4398, 5281, 6252, 7309, 8449, 9668, 10961]\n [7, 17, 44, 98, 194, 359, 639, 1106, 1865, 3061  …  7586, 11468, 16907, 24353, 34338, 47483, 64505, 86224, 113570, 147590]\n [23, 34, 41, 50, 76, 155, 375, 943, 2318, 5456  …  26126, 53285, 104101, 195476, 353979, 620137, 1054142, 1743299, 2811586, 4431746]\n [9, 19, 33, 48, 60, 64, 54, 23, -37, -135  …  -486, -762, -1122, -1580, -2151, -2851, -3697, -4707, -5900, -7296]\n [12, 15, 21, 49, 138, 352, 778, 1528, 2774, 4870  …  16072, 31448, 63860, 131720, 271603, 555820, 1128761, 2284679, 4637247, 9488786]\n [15, 34, 61, 103, 183, 355, 725, 1476, 2893, 5379  …  15646, 24421, 35778, 48745, 60485, 64947, 50896, -867, -121319, -358325]\n [11, 13, 20, 35, 61, 101, 158, 235, 335, 461  …  803, 1025, 1285, 1586, 1931, 2323, 2765, 3260, 3811, 4421]\n [0, -2, -5, -17, -38, -48, -1, 167, 503, 959  …  680, -2193, -9841, -26210, -57218, -111414, -200940, -343079, -562875, -897600]\n ⋮\n [2, 4, 9, 29, 91, 243, 572, 1253, 2658, 5564  …  23355, 46127, 88207, 162972, 290975, 502778, 842556, 1372601, 2178865, 3377691]\n [19, 28, 43, 83, 186, 425, 932, 1938, 3857, 7477  …  27727, 53828, 104630, 201866, 383348, 712223, 1290098, 2275087, 3905963, 6533710]\n [10, 8, 4, 14, 77, 263, 688, 1540, 3115, 5867  …  18275, 31653, 56195, 104783, 207024, 428953, 912587, 1952373, 4138229, 8616090]\n [21, 29, 44, 83, 185, 422, 910, 1828, 3470, 6393  …  22362, 44018, 89188, 182562, 370687, 737235, 1426389, 2677512, 4875117, 8619151]\n [21, 31, 47, 88, 193, 432, 925, 1892, 3767, 7411  …  27741, 51929, 93998, 163636, 273125, 436329, 666183, 969881, 1340718, 1745257]\n [15, 13, 2, -11, 7, 129, 482, 1261, 2743, 5301  …  15701, 24895, 37897, 55770, 79757, 111295, 152029, 203826, 268789, 349271]\n [-8, -11, -14, -17, -20, -23, -26, -29, -32, -35  …  -41, -44, -47, -50, -53, -56, -59, -62, -65, -68]\n [18, 28, 36, 48, 72, 122, 228, 449, 886, 1692  …  5298, 8652, 13434, 19892, 28155, 38138, 49420, 61092, 71572, 78384]\n [14, 23, 47, 104, 221, 446, 873, 1686, 3232, 6142  …  21353, 39008, 70604, 127566, 232240, 429598, 810693, 1557495, 3024738, 5883107]\n [16, 29, 52, 81, 108, 121, 105, 56, 45, 420  …  8809, 27076, 72420, 174990, 390905, 820690, 1641111, 3163610, 5947757, 11028712]\n [21, 29, 40, 58, 84, 112, 134, 159, 245, 535  …  2841, 5664, 10389, 18477, 34425, 71752, 166672, 405377, 971947, 2221091]\n [-6, -14, -27, -33, -7, 89, 306, 708, 1372, 2388  …  5901, 8643, 12227, 16808, 22554, 29646, 38278, 48657, 61003, 75549]\n```\n:::\n:::\n\n\n## Part 1\n\n### The problem and solution\n\nGather all the last differences and extrapolate another number in each sequence.\n\n::: {.cell execution_count=4}\n``` {.julia .cell-code}\nnext_num_in_seq = Int64[];\nfor cur_seq in input_data\n    last_differences = Int64[];\n\n    cur_diff = diff(cur_seq);\n    while !all(cur_diff .== 0)\n        push!(last_differences, cur_diff[end]);\n        cur_diff = diff(cur_diff);\n    end\n\n    push!(last_differences, cur_seq[end]);\n    next_diff = 0;\n    for i in last_differences\n        next_diff += i;\n    end\n    push!(next_num_in_seq, next_diff);\nend\n```\n:::\n\n\n::: {.cell execution_count=5}\n\n::: {.cell-output .cell-output-display execution_count=6}\nThe sum of the extrapolated values is: 1789635132.\n\n:::\n:::\n\n\n# Part 2\n\n### The problem and solution\n\nGather all the first differences and extrapolate previous number in each sequence.\n\n::: {.cell execution_count=6}\n``` {.julia .cell-code}\nprev_num_in_seq = Int64[];\nfor cur_seq in input_data\n    first_differences = Int64[];\n\n    cur_diff = diff(cur_seq);\n    while !all(cur_diff .== 0)\n        push!(first_differences, cur_diff[begin]);\n        cur_diff = diff(cur_diff);\n    end\n\n    first_differences = first_differences[end:-1:1];\n    push!(first_differences, cur_seq[begin]);\n    prev_diff = 0;\n    for i in first_differences\n        prev_diff = i - prev_diff;\n    end\n    push!(prev_num_in_seq, prev_diff);\nend\n```\n:::\n\n\n::: {.cell execution_count=7}\n\n::: {.cell-output .cell-output-display execution_count=8}\nThe sum of the extrapolated values is: 913.\n\n:::\n:::\n\n\n",
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+      "Day_09_files/figure-html"
+    ],
+    "filters": [],
+    "includes": {}
+  }
+}