From 605b74a270d1193e7988496156e8bf878703ca11 Mon Sep 17 00:00:00 2001
From: Georgios Samaras <gsmrs@protonmail.com>
Date: Sat, 14 Dec 2024 12:52:46 +0100
Subject: [PATCH] day 14

---
 CMakeLists.txt   |   2 +-
 day-14/input.txt | 500 +++++++++++++++++++++++++++++++++++++++++++++++
 day-14/main.c    | 168 ++++++++++++++++
 day-14/test.txt  |  12 ++
 4 files changed, 681 insertions(+), 1 deletion(-)
 create mode 100644 day-14/input.txt
 create mode 100644 day-14/main.c
 create mode 100644 day-14/test.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 052c647..57de953 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,5 +10,5 @@ foreach(DAY_DIR ${DAY_DIRS})
     get_filename_component(DAY ${DAY_DIR} NAME)
     message("DAY: ${DAY}")
     add_executable(${DAY} ${DAY_DIR}/main.c)
-    target_link_libraries(${DAY} aoc)
+    target_link_libraries(${DAY} aoc m)
 endforeach()
diff --git a/day-14/input.txt b/day-14/input.txt
new file mode 100644
index 0000000..850dcd8
--- /dev/null
+++ b/day-14/input.txt
@@ -0,0 +1,500 @@
+p=52,66 v=37,34
+p=0,87 v=41,-19
+p=92,102 v=-26,86
+p=7,12 v=-16,-17
+p=85,34 v=81,38
+p=80,28 v=88,-61
+p=25,20 v=27,92
+p=28,45 v=-80,66
+p=72,86 v=47,-85
+p=36,2 v=28,30
+p=36,29 v=28,69
+p=84,102 v=-26,86
+p=52,73 v=68,-91
+p=26,38 v=-68,-69
+p=54,100 v=65,-70
+p=99,77 v=-1,-42
+p=50,59 v=-94,87
+p=65,34 v=47,-96
+p=87,100 v=-78,86
+p=25,31 v=-62,7
+p=78,8 v=67,-69
+p=19,59 v=-28,9
+p=85,61 v=-17,84
+p=20,28 v=-25,13
+p=25,21 v=-68,-50
+p=34,30 v=9,32
+p=91,15 v=-4,45
+p=2,58 v=-60,56
+p=52,89 v=-21,-79
+p=59,11 v=-88,23
+p=64,45 v=-91,72
+p=42,102 v=-15,-92
+p=64,56 v=99,-36
+p=69,36 v=10,-15
+p=22,74 v=-74,-13
+p=74,32 v=-11,-15
+p=49,37 v=-9,-48
+p=31,55 v=70,-78
+p=15,75 v=-65,-38
+p=69,38 v=54,-69
+p=32,36 v=93,68
+p=36,96 v=67,23
+p=57,96 v=-82,-67
+p=6,88 v=48,30
+p=13,67 v=76,87
+p=32,34 v=-67,-87
+p=87,41 v=-57,11
+p=1,14 v=54,-99
+p=88,51 v=34,50
+p=73,80 v=38,56
+p=19,95 v=88,27
+p=80,71 v=-66,-82
+p=79,30 v=84,54
+p=24,22 v=91,-55
+p=56,27 v=-27,1
+p=69,80 v=4,46
+p=50,78 v=-85,84
+p=7,27 v=51,29
+p=71,78 v=47,96
+p=86,90 v=-23,58
+p=31,37 v=6,19
+p=47,31 v=-95,16
+p=33,91 v=-89,80
+p=36,64 v=-3,6
+p=80,50 v=-38,25
+p=54,84 v=28,21
+p=77,26 v=58,81
+p=43,43 v=68,56
+p=60,95 v=-48,71
+p=95,25 v=5,-57
+p=80,95 v=-45,78
+p=66,29 v=-20,82
+p=99,76 v=-7,-91
+p=81,31 v=-69,-88
+p=76,57 v=-75,94
+p=82,17 v=-66,-5
+p=86,13 v=-13,21
+p=12,94 v=-89,51
+p=21,30 v=61,72
+p=7,98 v=-35,-79
+p=64,92 v=-41,27
+p=16,54 v=-27,-53
+p=69,56 v=-35,-67
+p=51,84 v=-33,99
+p=87,98 v=78,64
+p=10,25 v=33,-75
+p=57,12 v=13,42
+p=9,98 v=-83,-23
+p=97,66 v=32,-75
+p=86,50 v=-29,22
+p=43,0 v=18,21
+p=90,23 v=29,-49
+p=18,63 v=77,-51
+p=61,58 v=-60,-44
+p=69,94 v=-94,33
+p=67,100 v=77,-8
+p=12,50 v=30,47
+p=57,96 v=-24,2
+p=60,95 v=25,-51
+p=9,4 v=3,-46
+p=4,22 v=94,60
+p=79,16 v=38,-93
+p=62,57 v=78,-72
+p=78,0 v=70,92
+p=7,91 v=-93,-25
+p=83,48 v=-57,34
+p=73,35 v=-51,-90
+p=5,32 v=94,-9
+p=89,36 v=-23,44
+p=36,33 v=-27,60
+p=90,98 v=-66,2
+p=81,9 v=93,58
+p=27,101 v=92,36
+p=72,39 v=96,-15
+p=48,75 v=-77,-52
+p=64,1 v=10,45
+p=31,75 v=-31,-99
+p=54,50 v=-92,-40
+p=82,78 v=23,46
+p=92,48 v=34,-65
+p=91,54 v=20,-84
+p=90,67 v=69,-88
+p=72,35 v=-60,-40
+p=18,76 v=55,-44
+p=25,101 v=-92,-73
+p=64,15 v=7,-77
+p=42,42 v=-67,66
+p=47,38 v=-95,44
+p=54,46 v=-45,-19
+p=25,0 v=37,-27
+p=0,55 v=23,-62
+p=41,66 v=43,-94
+p=58,89 v=-61,11
+p=41,90 v=-58,52
+p=29,83 v=-37,2
+p=50,45 v=16,6
+p=59,6 v=65,-83
+p=78,84 v=37,73
+p=2,24 v=-58,-46
+p=100,30 v=8,-96
+p=13,55 v=64,65
+p=84,83 v=78,-1
+p=16,46 v=79,38
+p=94,34 v=-1,75
+p=36,82 v=-58,-85
+p=4,52 v=25,-64
+p=31,101 v=49,5
+p=89,6 v=26,36
+p=46,97 v=58,-64
+p=65,5 v=74,55
+p=24,37 v=-25,41
+p=40,89 v=67,24
+p=84,5 v=29,-48
+p=26,94 v=81,98
+p=51,8 v=-21,-84
+p=10,82 v=-51,-32
+p=56,89 v=50,-6
+p=53,13 v=-58,68
+p=47,36 v=-73,85
+p=59,68 v=16,-60
+p=1,83 v=54,-63
+p=43,6 v=-67,-49
+p=2,68 v=51,9
+p=58,42 v=40,-75
+p=10,71 v=-22,-26
+p=17,79 v=-80,59
+p=28,12 v=24,-11
+p=1,100 v=26,84
+p=58,99 v=16,67
+p=54,8 v=-79,-92
+p=69,26 v=81,-58
+p=11,7 v=47,-41
+p=87,15 v=-99,26
+p=60,20 v=-40,-24
+p=71,92 v=3,37
+p=97,82 v=-41,40
+p=54,12 v=-30,-27
+p=32,17 v=61,82
+p=54,95 v=-38,-16
+p=42,26 v=-67,57
+p=22,45 v=73,69
+p=18,0 v=-22,-92
+p=70,39 v=19,95
+p=63,72 v=10,21
+p=26,88 v=24,46
+p=4,101 v=75,43
+p=31,31 v=30,-12
+p=71,10 v=43,-86
+p=68,42 v=-2,94
+p=90,76 v=-38,68
+p=71,76 v=63,-13
+p=35,76 v=-21,6
+p=95,28 v=35,-77
+p=22,7 v=-52,-8
+p=23,56 v=-8,69
+p=54,45 v=-76,-90
+p=56,64 v=-91,-75
+p=28,39 v=-41,77
+p=42,51 v=-12,19
+p=28,67 v=12,-44
+p=86,52 v=75,-84
+p=69,54 v=71,90
+p=42,70 v=-52,-25
+p=14,48 v=16,-96
+p=1,65 v=-26,-72
+p=80,34 v=-39,-6
+p=78,15 v=41,-33
+p=13,5 v=-7,64
+p=28,80 v=-40,18
+p=43,15 v=40,-8
+p=98,68 v=-6,82
+p=16,32 v=86,11
+p=66,56 v=65,75
+p=84,58 v=48,-33
+p=65,22 v=-63,-84
+p=93,52 v=-75,72
+p=17,23 v=-68,-74
+p=77,65 v=-8,-66
+p=61,37 v=-42,69
+p=86,8 v=66,-20
+p=4,7 v=-44,70
+p=15,82 v=9,-23
+p=67,95 v=-95,57
+p=5,24 v=69,4
+p=58,96 v=99,46
+p=38,21 v=50,56
+p=60,76 v=-64,74
+p=29,0 v=-55,-25
+p=24,13 v=65,71
+p=48,76 v=-67,37
+p=19,39 v=-62,29
+p=33,58 v=6,28
+p=29,38 v=-98,-68
+p=50,55 v=-55,65
+p=5,77 v=91,71
+p=99,38 v=-8,77
+p=58,47 v=16,44
+p=43,45 v=12,-31
+p=21,102 v=45,-20
+p=79,99 v=83,-46
+p=52,56 v=83,16
+p=56,27 v=74,-68
+p=17,20 v=82,-77
+p=62,8 v=13,95
+p=58,24 v=-48,-2
+p=86,68 v=-3,-37
+p=2,24 v=63,-8
+p=1,81 v=-41,-88
+p=15,40 v=-25,66
+p=77,97 v=-23,5
+p=48,4 v=34,42
+p=41,74 v=-3,-91
+p=90,53 v=44,-76
+p=50,42 v=-79,13
+p=77,67 v=17,-53
+p=69,3 v=-8,3
+p=89,60 v=-8,19
+p=15,93 v=54,-32
+p=11,24 v=36,63
+p=22,6 v=-52,79
+p=11,101 v=-80,-79
+p=79,87 v=-8,77
+p=46,97 v=13,61
+p=90,25 v=-45,7
+p=46,95 v=13,-23
+p=89,62 v=-72,-94
+p=32,100 v=-49,58
+p=58,30 v=68,-40
+p=97,28 v=11,37
+p=76,61 v=-88,-31
+p=6,45 v=-7,38
+p=79,34 v=-69,-90
+p=96,76 v=57,-29
+p=9,100 v=-7,55
+p=59,23 v=50,43
+p=19,7 v=33,-74
+p=45,43 v=86,66
+p=50,19 v=56,33
+p=28,65 v=-9,-89
+p=14,2 v=-74,-33
+p=91,98 v=-50,99
+p=93,80 v=94,-48
+p=55,81 v=-7,-20
+p=57,100 v=-30,-39
+p=62,76 v=68,-38
+p=15,20 v=-77,-90
+p=37,33 v=89,60
+p=18,101 v=-3,20
+p=56,65 v=71,-60
+p=26,26 v=-58,-99
+p=33,75 v=-49,-91
+p=10,71 v=-56,-34
+p=25,83 v=39,-6
+p=13,17 v=37,61
+p=98,95 v=2,80
+p=26,83 v=-49,-35
+p=9,27 v=-72,46
+p=27,73 v=-9,40
+p=71,5 v=-94,-89
+p=60,6 v=-21,30
+p=10,68 v=-82,-31
+p=87,45 v=-38,66
+p=55,46 v=-68,-93
+p=34,77 v=55,-63
+p=5,51 v=38,31
+p=3,65 v=94,-16
+p=70,24 v=-48,10
+p=89,78 v=-75,40
+p=32,39 v=3,66
+p=28,94 v=40,-36
+p=91,38 v=-35,66
+p=29,66 v=-94,-50
+p=90,80 v=63,74
+p=15,31 v=-95,78
+p=50,19 v=7,-71
+p=58,64 v=-5,68
+p=16,64 v=65,-35
+p=46,93 v=-59,-22
+p=65,5 v=53,-33
+p=10,83 v=84,47
+p=23,12 v=49,-76
+p=58,14 v=-36,-80
+p=49,4 v=28,17
+p=62,43 v=-39,56
+p=61,11 v=-36,-52
+p=60,72 v=71,87
+p=44,56 v=-85,-76
+p=37,88 v=-3,27
+p=10,35 v=-90,-18
+p=14,40 v=30,-34
+p=22,95 v=27,95
+p=32,92 v=-37,2
+p=54,3 v=-54,-82
+p=98,5 v=11,-24
+p=39,76 v=37,90
+p=69,15 v=47,45
+p=56,40 v=-79,13
+p=80,41 v=63,32
+p=11,85 v=-7,74
+p=24,45 v=46,-50
+p=98,49 v=-38,-81
+p=26,45 v=-26,-80
+p=2,87 v=60,6
+p=93,74 v=26,-16
+p=24,70 v=-28,-85
+p=59,21 v=-63,62
+p=44,74 v=-7,14
+p=75,94 v=47,-86
+p=84,16 v=6,41
+p=17,79 v=33,-44
+p=5,72 v=18,58
+p=96,11 v=8,17
+p=34,48 v=62,14
+p=17,36 v=-42,-64
+p=87,55 v=93,65
+p=84,1 v=75,52
+p=30,74 v=-5,-33
+p=34,22 v=-32,-91
+p=85,94 v=-51,17
+p=37,90 v=-9,55
+p=9,85 v=-58,-37
+p=58,30 v=-2,72
+p=90,55 v=-53,-78
+p=34,48 v=-8,-33
+p=76,62 v=13,18
+p=16,21 v=76,-99
+p=42,71 v=46,68
+p=95,9 v=-75,64
+p=63,99 v=62,-39
+p=73,97 v=68,92
+p=79,17 v=-17,-39
+p=16,54 v=27,90
+p=48,34 v=9,-49
+p=88,72 v=51,59
+p=94,24 v=62,-43
+p=93,37 v=22,24
+p=90,80 v=-23,15
+p=10,98 v=88,80
+p=60,9 v=65,64
+p=44,80 v=21,68
+p=32,3 v=-95,83
+p=83,13 v=78,1
+p=20,49 v=70,-94
+p=51,82 v=-30,71
+p=31,12 v=61,86
+p=67,51 v=4,3
+p=19,25 v=67,76
+p=96,6 v=-99,-11
+p=35,13 v=-98,-42
+p=89,13 v=-29,95
+p=73,73 v=-60,87
+p=50,4 v=77,98
+p=5,86 v=61,49
+p=14,56 v=-7,40
+p=97,4 v=8,-64
+p=19,67 v=-37,-47
+p=61,23 v=-88,60
+p=23,11 v=-59,11
+p=11,16 v=33,-9
+p=90,29 v=-12,75
+p=81,62 v=-9,51
+p=34,60 v=58,84
+p=46,16 v=58,67
+p=47,12 v=74,67
+p=33,50 v=-31,87
+p=76,32 v=-52,-66
+p=56,39 v=-79,88
+p=92,18 v=-75,63
+p=9,17 v=36,70
+p=70,42 v=-11,74
+p=11,8 v=46,69
+p=30,19 v=64,-5
+p=78,42 v=-45,-46
+p=98,64 v=-99,-66
+p=83,31 v=14,-39
+p=97,66 v=73,96
+p=33,55 v=46,-38
+p=67,59 v=59,3
+p=19,34 v=82,-37
+p=9,77 v=45,46
+p=88,100 v=29,55
+p=77,2 v=-54,-42
+p=59,49 v=-79,-53
+p=22,83 v=94,99
+p=75,40 v=99,-15
+p=44,33 v=-28,2
+p=83,42 v=44,-65
+p=61,13 v=-7,-8
+p=39,25 v=-90,93
+p=18,11 v=32,98
+p=49,24 v=3,32
+p=75,30 v=99,85
+p=48,21 v=52,40
+p=5,23 v=91,-52
+p=40,41 v=92,-62
+p=14,51 v=-34,-41
+p=17,86 v=30,27
+p=77,15 v=-11,-80
+p=26,18 v=-77,73
+p=26,42 v=26,-25
+p=10,97 v=27,80
+p=24,37 v=-40,-65
+p=75,40 v=-81,-43
+p=6,19 v=57,38
+p=16,82 v=-74,-85
+p=87,81 v=-32,15
+p=36,91 v=53,-60
+p=25,32 v=6,-71
+p=11,69 v=-41,65
+p=31,81 v=-22,33
+p=7,51 v=-88,-93
+p=75,18 v=84,-30
+p=59,65 v=-33,-22
+p=53,19 v=87,-14
+p=53,98 v=-30,55
+p=69,88 v=-27,-12
+p=34,93 v=-37,52
+p=16,17 v=11,65
+p=65,53 v=-33,-28
+p=81,45 v=-66,-5
+p=97,92 v=18,-58
+p=88,18 v=72,1
+p=72,62 v=-34,64
+p=79,70 v=29,26
+p=64,66 v=7,75
+p=48,65 v=-89,-68
+p=47,18 v=-7,-64
+p=50,89 v=-73,-64
+p=13,91 v=33,29
+p=63,6 v=-45,42
+p=84,22 v=84,-71
+p=68,100 v=53,5
+p=89,66 v=-55,59
+p=66,19 v=-17,95
+p=49,16 v=61,-60
+p=16,15 v=58,70
+p=38,12 v=-37,47
+p=98,44 v=81,-75
+p=34,72 v=-3,28
+p=36,54 v=16,31
+p=48,63 v=55,6
+p=14,68 v=33,90
+p=18,67 v=-1,-53
+p=10,35 v=58,59
+p=13,67 v=57,-38
+p=48,69 v=83,90
+p=88,17 v=-75,26
+p=69,72 v=-98,54
+p=87,12 v=-48,16
+p=99,2 v=14,64
+p=71,97 v=47,39
+p=69,64 v=14,-3
+p=36,82 v=38,-93
+p=24,77 v=21,-10
+p=10,21 v=-34,-30
+p=34,44 v=-98,47
+p=38,9 v=-39,-74
+p=76,21 v=44,60
+p=66,75 v=-33,-66
+p=26,31 v=9,-40
diff --git a/day-14/main.c b/day-14/main.c
new file mode 100644
index 0000000..402f97d
--- /dev/null
+++ b/day-14/main.c
@@ -0,0 +1,168 @@
+#include "aoc.h"
+
+typedef struct {
+    i32 x, y;
+    i32 vx, vy;
+} Robot;
+
+static void
+parse_pair(str s, i32 *x, i32 *y, Arena arena) {
+    s = str_sub(s, 2, s.len);
+    str lhs, rhs;
+    str_split(s, STR(","), &lhs, &rhs);
+    *x = (i32) parse_i64(lhs, arena);
+    *y = (i32) parse_i64(rhs, arena);
+}
+
+static Robot
+parse_robot(str line, Arena arena) {
+    str p, v;
+    str_split(line, STR(" "), &p, &v);
+    Robot robot;
+    parse_pair(p, &robot.x, &robot.y, arena);
+    parse_pair(v, &robot.vx, &robot.vy, arena);
+    return robot;
+}
+
+static void
+dump_grid(Arena arena, Robot *robots, isize count, int width, int height) {
+    u8 *grid = ARENA_ALLOC_ARRAY(&arena, u8, width * height);
+
+    for (isize i = 0; i < count; i++) {
+        Robot *r = &robots[i];
+        grid[r->y * width + r->x]++;
+    }
+
+    for (int y = 0; y < height; y++) {
+        for (int x = 0; x < width; x++) {
+            u8 count = grid[y * width + x];
+            if (count == 0) {
+                putchar('.');
+            } else {
+                putchar('0' + count);
+            }
+        }
+        putchar('\n');
+    }
+}
+
+static void
+step(Robot *robots, isize count, int width, int height) {
+    for (isize i = 0; i < count; i++) {
+        Robot *r = &robots[i];
+        r->x = (r->x + r->vx + width) % width;
+        r->y = (r->y + r->vy + height) % height;
+    }
+}
+
+static bool
+has_tree(u8 *grid, int width, int height) {
+    for (int x = 0; x < width; x++) {
+        i32 consecutive = 0;
+        for (int y = 1; y < height; y++) {
+            if (grid[y * width + x] && grid[(y - 1) * width + x]) {
+                consecutive++;
+            } else {
+                consecutive = 0;
+            }
+            if (consecutive >= width / 4) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+static f32
+compute_entropy(u8 *grid, int width, int height) {
+    i32 counts[256] = {0};
+    for (int i = 0; i < width * height; i++) {
+        counts[grid[i]]++;
+    }
+    f32 entropy = 0.0f;
+    for (int i = 0; i < 256; i++) {
+        if (counts[i]) {
+            f32 prob = (f32) counts[i] / (f32) (width * height);
+            entropy -= prob * log2f(prob);
+        }
+    }
+    return entropy;
+}
+
+int main(int argc, char **argv) {
+    Arena *arena = make_arena(Megabytes(1));
+    Tokens lines = read_lines(arena, argv[1]);
+
+    int count = lines.len;
+    bool is_example = true;
+
+    Robot *robots = ARENA_ALLOC_ARRAY(arena, Robot, lines.len);
+    for (isize i = 0; i < lines.len; i++) {
+        robots[i] = parse_robot(str_trim(lines.tokens[i]), *arena);
+        if (robots[i].x >= 11) {
+            is_example = false;
+        }
+    }
+    int width = is_example ? 11 : 101;
+    int height = is_example ? 7 : 103;
+    ASSERT(width % 2 == 1);
+    ASSERT(height % 2 == 1);
+
+    /* dump_grid(*arena, robots, count, width, height); */
+    /* puts(""); */
+
+    i64 second = 0;
+    for (int i = 0; i < 100; i++) {
+        step(robots, count, width, height);
+        second++;
+    }
+
+    int cx = width / 2;
+    int cy = height / 2;
+
+    i64 counts[4] = {0};
+    for (isize i = 0; i < count; i++) {
+        Robot *r = &robots[i];
+        if (r->x != width / 2 && r->y != height / 2) {
+            int qx = r->x < cx ? 0 : 1;
+            int qy = r->y < cy ? 0 : 1;
+            counts[qy * 2 + qx]++;
+        }
+    }
+
+    i64 part_1  = counts[0] * counts[1] * counts[2] * counts[3];
+    printf("%ld\n", part_1);
+
+    // Part 2
+    u8 *grid = ARENA_ALLOC_ARRAY(arena, u8, width * height);
+    f32 best = 1.0f;
+    i32 best_second = 0;
+    i64 part_2 = 0;
+    for (;;) {
+        step(robots, count, width, height);
+        second++;
+        memset(grid, 0, width * height);
+        for (isize i = 0; i < count; i++) {
+            Robot *r = &robots[i];
+            grid[r->y * width + r->x]++;
+        }
+#if 0
+        f32 entropy = compute_entropy(grid, width, height);
+        if (entropy < best) {
+            best = entropy;
+            best_second = second;
+            printf("%ld %f\n", second, entropy);
+            dump_grid(*arena, robots, count, width, height);
+            puts("--------------------");
+        }
+#else
+        if (has_tree(grid, width, height)) {
+            printf("Tree detected on second %ld\n", second);
+            part_2 = second;
+            break;
+        }
+#endif
+    }
+    dump_grid(*arena, robots, count, width, height);
+    printf("%ld\n", part_2);
+}
diff --git a/day-14/test.txt b/day-14/test.txt
new file mode 100644
index 0000000..2455da4
--- /dev/null
+++ b/day-14/test.txt
@@ -0,0 +1,12 @@
+p=0,4 v=3,-3
+p=6,3 v=-1,-3
+p=10,3 v=-1,2
+p=2,0 v=2,-1
+p=0,0 v=1,3
+p=3,0 v=-2,-2
+p=7,6 v=-1,-3
+p=3,0 v=-1,-2
+p=9,3 v=2,3
+p=7,3 v=-1,2
+p=2,4 v=2,-3
+p=9,5 v=-3,-3