day 3 pt1

1 files changed, 235 insertions, 0 deletions

diff --git a/day3.zig b/day3.zig
new file mode 100644
index 0000000..b078f76
--- /dev/null
+++ b/day3.zig
@@ -0,0 +1,235 @@
+const std = @import("std");
+const Setup = @import("common.zig").Setup;
+
+pub fn main() !void {
+    // var setup = try Setup.get();
+    // defer setup.deinit();
+    try std.fmt.format(std.io.getStdOut().writer(), "day 3: {}\n", .{try solve(std.heap.page_allocator, input2)});
+}
+
+const Grid = struct {
+    buf: []const u8,
+    width: usize,
+    height: usize,
+
+    fn init(input: []const u8) !Grid {
+        const height = std.mem.count(u8, input, "\n")+1;
+        const width = std.mem.indexOfScalar(u8, input, '\n') orelse return error.NoNewlines;
+        return .{
+            .buf = input,
+            .width = width,
+            .height = height,
+        };
+    }
+    fn get(self: Grid, x: usize, y: usize) ?u8 {
+        if (x >= self.width) return null;
+        if (y >= self.height) return null;
+        // width +1 becuase the buffer still has newlines in it
+        return self.buf[@intCast((self.width+1) * y + x)];
+    }
+};
+
+fn solve(a: std.mem.Allocator, input: []const u8) !u32 {
+    var spanBuf = std.ArrayList(u8).init(a);
+    defer spanBuf.deinit();
+    const grid = try Grid.init(input);
+    var sum: u32 = 0;
+    for (0..grid.height) |y| {
+        spanBuf.clearRetainingCapacity();
+        for (0..grid.width) |x| {
+            const ch = grid.get(x, y) orelse return error.IndexError;
+            if (std.ascii.isDigit(ch)) {
+                try spanBuf.append(ch);
+            } 
+            // end-of-span, either hit a non-digit or end of line
+            if ((!std.ascii.isDigit(ch) or (x==grid.width-1)) and spanBuf.items.len > 0) {
+                const num = try std.fmt.parseInt(u32, spanBuf.items, 10);
+                const num_len = spanBuf.items.len;
+                spanBuf.clearRetainingCapacity();
+                // now check all the surrounding positions including diagonals, for non-digits and points
+                const search_x_end = x;
+                const search_x_start = std.math.sub(usize, search_x_end, (num_len+1)) catch search_x_end-num_len;
+                const is_part: bool = br: for (search_x_start..(search_x_end)+1) |x_p| {
+                    const search_y_start = std.math.sub(usize, y, 1) catch y;
+                    const search_y_end = y+1;
+                    for (search_y_start..(search_y_end+1)) |y_p| {
+                        if (grid.get(x_p, y_p)) |adj| {
+                            if (!std.ascii.isDigit(adj) and adj != '.') {
+                                //std.log.info("found symbol {c} next to num {}", .{adj, num});
+                                break :br true;
+                            }
+                        }
+                    }
+                } else {
+                    //std.log.info("no symbol next to num {}", .{num});
+                    break :br false;
+                };
+                if (is_part) {
+                    sum += num;
+                }
+            }
+        }
+    }
+    return sum;
+}
+
+
+
+test {
+    const input = 
+    \\467..114..
+    \\...*......
+    \\..35..633.
+    \\......#...
+    \\617*......
+    \\.....+.58.
+    \\..592.....
+    \\......755.
+    \\...$.*....
+    \\.664.598..
+    ;
+    try std.testing.expectEqual(@as(u32, 4361), try solve(std.testing.allocator, input));
+}
+
+const input2 = 
+\\.......497...........................858...923...128..................227..801........487.....664...........................................
+\\436........765..............140.......+....................859.............*.........+.................960........668.......................
+\\...*982...........=..........=....203......266.263...375*....=...402....691..-....................*..........575....................13......
+\\.............114...588...............*............*......631........*.......952...463..14.......661..........=...706......*333.........595..
+\\...194.........*..............743...917.&......375.....................................*...............544*.......*....664..................
+\\...*.....807..452....81..........*......969..#......309*................/....873....941...828.197..........427.728...............566...13...
+\\.243........*.....80.......329....470.......145.475.....111........*659..259....+........*....%........569..............%.....*....*....*...
+\\.........130......*....385*............123......................199.......................640.....463..%.........978....920...266..380.83...
+\\.....323........870.........+...........$.........466......453........................297...........*............*..........................
+\\........*.=..............588.....*786......$.........*........*.......390*.....886...*....227...728..852.......606....*863.......916..396...
+\\.....538...287................301........133.....539..........33.537......466..$...793..+..........*...............218.....721........*.....
+\\...............986.........=.......................................*...%...............222..-.......701.271...............#.........437.....
+\\......*3.........*.626.68...419...740...........................806...976.......875.........174..............735.............=488...........
+\\...790.........487....*................./532..13............................*....-.....503..........*11..734..........978.19......622.......
+\\...................&....712.68=.619+.........*.......................863...596.....2.....*.......160.....+...&659........*.........-....-757
+\\437*.......#........520...*..........304....568.974.255.318.183.........*.......&.....675......................................849..........
+\\....161.....687.710.....854.............*.......*......*....&...441......891.....476..........616.......$........235..434.880...*..673+.....
+\\..................*...............683.....800.120..............*....807..................................707.....*....-....*...74........562
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+\\...*......121........=.....*.......$......909.......583............128........929...................765.............*............+....24....
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+\\............595........................*.......*...................833*..............%.......973..$....@...*.268........506*..........251...
+\\967...................................25....234...........................306....281..........=..36..918.432....../406........344...$.......
+\\.....700*610.......=...839......917......33......610@................537....=....@............................%........20.402.@.....926.....
+\\..............%.768...*....................*...@............93..161.%...............74$......%.........96..298..........%..+............+519
+\\...........925.......586...................264..85...721....*...*.............................371.................822.=.....................
+\\...............540...........-....447....................987.....305.............379@.707..............670...397...*..842....552.464........
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+\\.....*...647...696..*..............203....................418.....19............522........*.......462................57...786..........561.
+\\....691.....$.......756...165.....................596.32...%........#..280.259$..........398..............425.............*....719..796.....
+\\.............../.........=........1/..305............*.........451......&..........332.......706............&.......327.841...........*.....
+\\.74..........791.............=........+.....................+...-..................+..........*.....................*...............419..371
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+\\............190..........*......385.............*....846......................907.826..585.......447.441..*..*............7......871........
+\\.................142....944....$.................634.............587..@..930..........*......935.....*...819.29.....3......*35..............
+\\......967....415*......................=980.....................%....58.-......317..74......../.....922..............-.207........../.......
+\\.........................................................................................................175....................369.233.....
+\\.........................+....645.$........%.....620.+429....951......616.................................*............524$.................
+\\....799...551*602........920..+....503..654....-...*............*....=......395.........451....263.......897..................370...........
+\\......-.......................................409......970....661.............*............+...*....48...................475..$........839..
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+\\........815....*...........................*452......./......................365.........929....*978.=................709........+..84......
+\\....427*......466.............608*796..............680......................*......&.........142.....603.................#......621..*......
+\\.........635............@....................302..................296-.....679...801..290..................464..............980......627....
+\\....../.../........%...850.......*108....513*........656...*739........715...............@.......713.......*...................*............
+\\354+..245.......629...........995.....................$..41.....=.....@.....................45..........840......506+...$.....148...........
+\\..........995.................................&541............914.510.....950...../...........*53..28...................275........138......
+\\.............*812..665...../.........................101.308..............*......691.482.............*........902.585.......@.......*.......
+\\.........../........./...292...............#..........-....*....@307......661..........*.210......135....932%...........992..54..191..931...
+\\...400..649...............................504.196.........88........................581.............................743*.............&......
+\\...*.........140..............642....891.............309...............................................695......361..............603........
+\\....170.643#..*.................*....*.......*24.....*....................932.291.....538....461.........*........*..275............&.......
+\\.............725......494......23...279...713..../....449............*........*...../...=......*..........434..............785..............
+\\.....991..........946.............................830.........136.439.24...519......289.......408...579........708.650*......*.370.13....410
+\\......*..887........#..688.673.........218......................-...............941....................$.......%.......927.722....*.........
+\\....124....*...........*..../....427....*.............312................................................922...........................307..
+\\...........706...16..934..*.......*......608....459..&..........761.....................647..641...........*.............242............*...
+\\..5*715..-........+........122.....262........./...........928....%............728..610*......*..502.....222..40.....923..+...........540...
+\\.........701.............=..............291...............*.........351.........*............141.%............*.../.....*....725............
+\\..............314.......878....%.......*......=..820*.....988..204.....-.....889......119............797...........395....+.............287.
+\\..................671........322....101......257.....733........@.....................=.............*..........544......600.......862.......
+\\..421.......582...%..............................484...............565.....+...831...........695...384.#...592.=............240....../.904..
+\\....*..........*........570...........&....=........*629......717&.*.......93......726../961....*......535..*........767../......715....*...
+\\....439.....630............../..%...615...912......................777............*..............602.........567..3........107....$..77.....
+\\....................914.....3...2.=.............763...&885......................185....182.......................*......-......+............
+\\...372...383........*..............60.............*............&..38.681...............*.....459....../........117...504......358..480-.....
+\\............+.990..33...........................834.......@..33......................494....*........181.66+................................
+\\...............*......*...492..............176..........857...........376.315................954.....................*982.......763.........
+\\329=..........179....245...*...61...........*...*................%......+....*.....352*509.........952#..69..620..423.............*.........
+\\.........................131.....*17......191.33.306...../.....144..503......491.............................................298...415......
+\\...................$...................................426.........*...............526.669.....&498..698...$............447.....+...........
+\\.............575...142.617......890..............%...............212..730.519.971..&......*384.........@....18.219.........*................
+\\.......*537..*.........*........*.........677...587..407...120*........./....*...................................+......334..........700....
+\\....944......636..848........743.....388..*....................109..........................................................540.40..*.......
+\\.................*....596............*....155..324...820.520.................=...............443...94...........621.276......*..+..910......
+\\...............276.....-.........376...........*........*....................739......368....=..............428....*......434..........878..
+\\932....28.....................-..=....207......959....................289.........196.*........................*...............-.......=....
+\\...*........................172....#.#.....688.........25..944...725...&............*..110.....148...426.483..771../932......800............
+\\.947............................457....931*.............-....*...#.......834......721.........*.........*.............................477...
+\\.....*491......*.........*114.................191.....$...213........909*...................194............633....%...792..605.633...#......
+\\.............108......611.....+719...........*.....696........865...............120................=724...%....950.../......*...../.........
+\\...320............*.................260/...121.........338...*........719.180.........516.....*.............................649.............
+\\.....#...643.......941......*160......................*......140...94....*...............*..39.789................*......&.........81...597.
+\\............*..135.......532.................%90...608............*............+515....743.............+...194.993.669..259..+..............
+\\.....%....948.....*............262..695.712....................623.....*...................473........602...*...............83......679.....
+\\..259.............447.............%.*...............363.............105...................@........=......+.........................*.......
+\\......957....659........299..........................%...599..898.+.................464.......606.237..768..416@....=...............228.....
+\\.376..$.........*..........*..2.........@557......./.......*.*.....517..........859*.........*....................855...877.427.........*...
+\\.........*468..535......500....$................117......726.381........428...$................@........43....472.......*...*...........476.
+\\......517................................951........%............-..249..@.....920...........859........*........*....825.393...15..........
+\\...........770.......&16.....278...417......$.....626...-23....954.....#..............................868.......502............*............
+\\.....373..*...................%...*.....254................................................246.#530....................982....179....635....
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+\\................+.....+................388....*..........................*....788............../..................220.............834.......
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+\\................*64........*.../..&.....924.........*........-...$....................203.............-...+..../...............*..423.&451..
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+\\.............................597...765................388......149..468.....+............698......*....143........................426.......
+\\.......................878...*.........875..............*..871*.....*..............929....................$.504*..............473.%.........
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+\\...#..............*.....459............212...18*964.*.........=71..........768..827............./.....*......................567............
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+\\.......877..636.....42......772..419.....189..*................&....*.....................=.17......366*....563......228...153..............
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+\\.....576......255..............593...397............469..%......#.......+568.......374......499....*...........541..477.........%137..*.....
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+\\..............*...769.....41*....922............................$..*.......271.........350..........677.346......................662....725.
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+\\.........%..90.................437..........848...........................*......714........708..........*223.588.....884....871.801........
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+\\.....50..481.........=.....643...........@......%............*.......815......681..263....*........*...5.....256*11.377$....872.903.*.......
+\\.....*...............635.......698..........583...148........708........................323.243..201.....................*..........377.132.
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+\\..................620............806......866.................559......440...........................310...........................590..547.
+;
\ No newline at end of file