AOC 2024: days 2-7

examples/aoc2024/day02/part1.jou

@@ -0,0 +1,66 @@
+import "stdlib/io.jou"
+import "stdlib/mem.jou"
+import "stdlib/math.jou"
+import "stdlib/str.jou"
+import "stdlib/ascii.jou"
+
+
+class Report:
+    data: int*
+    len: int
+
+    def free(self) -> None:
+        free(self->data)
+
+    def is_safe(self) -> bool:
+        inc = True
+        dec = True
+
+        for i = 0; i < self->len - 1; i++:
+            d = self->data[i+1] - self->data[i]
+
+            if d <= 0:
+                inc = False
+            if d >= 0:
+                dec = False
+
+            if not (1 <= abs(d) and abs(d) <= 3):
+                return False
+
+        return inc or dec
+
+
+# mutates the line in-place through split_by_ascii_whitespace()
+def parse_report(line: byte*) -> Report:
+    words = split_by_ascii_whitespace(line)
+
+    n = 0
+    while words[n] != NULL:
+        n++
+
+    report = Report{len=n}
+    report.data = malloc(sizeof(report.data[0]) * n)
+    for i = 0; i < n; i++:
+        report.data[i] = atoi(words[i])
+
+    free(words)
+    return report
+
+
+def main() -> int:
+    f = fopen("sampleinput.txt", "r")
+    assert f != NULL
+
+    num_safe = 0
+
+    line: byte[1024]
+    while fgets(line, sizeof(line) as int, f) != NULL:
+        report = parse_report(line)
+        if report.is_safe():
+            num_safe++
+        report.free()
+
+    printf("%d\n", num_safe)  # Output: 2
+
+    fclose(f)
+    return 0

examples/aoc2024/day02/part2.jou

@@ -0,0 +1,84 @@
+import "stdlib/io.jou"
+import "stdlib/mem.jou"
+import "stdlib/math.jou"
+import "stdlib/str.jou"
+import "stdlib/ascii.jou"
+
+
+class Report:
+    data: int*
+    len: int
+
+    def free(self) -> None:
+        free(self->data)
+
+    def is_safe(self) -> bool:
+        inc = True
+        dec = True
+
+        for i = 0; i < self->len - 1; i++:
+            d = self->data[i+1] - self->data[i]
+
+            if d <= 0:
+                inc = False
+            if d >= 0:
+                dec = False
+
+            if not (1 <= abs(d) and abs(d) <= 3):
+                return False
+
+        return inc or dec
+
+    def pop(self, i: int) -> int:
+        bye = self->data[i]
+        memmove(&self->data[i], &self->data[i+1], sizeof(self->data[0]) * (--self->len - i))
+        return bye
+
+    def insert(self, i: int, value: int) -> None:
+        # assumes there is enough room in the array and no reallocation is needed
+        memmove(&self->data[i+1], &self->data[i], sizeof(self->data[0]) * (self->len++ - i))
+        self->data[i] = value
+
+
+# mutates the line in-place through split_by_ascii_whitespace()
+def parse_report(line: byte*) -> Report:
+    words = split_by_ascii_whitespace(line)
+
+    n = 0
+    while words[n] != NULL:
+        n++
+
+    report = Report{len=n}
+    report.data = malloc(sizeof(report.data[0]) * n)
+    for i = 0; i < n; i++:
+        report.data[i] = atoi(words[i])
+
+    free(words)
+    return report
+
+
+def main() -> int:
+    f = fopen("sampleinput.txt", "r")
+    assert f != NULL
+
+    num_safe = 0
+
+    line: byte[1024]
+    while fgets(line, sizeof(line) as int, f) != NULL:
+        report = parse_report(line)
+        if report.is_safe():
+            num_safe++
+        else:
+            for i = 0; i < report.len; i++:
+                temp_missing = report.pop(i)
+                if report.is_safe():
+                    num_safe++
+                    break
+                report.insert(i, temp_missing)
+
+        report.free()
+
+    printf("%d\n", num_safe)  # Output: 4
+
+    fclose(f)
+    return 0

examples/aoc2024/day02/sampleinput.txt

@@ -0,0 +1,6 @@
+7 6 4 2 1
+1 2 7 8 9
+9 7 6 2 1
+1 3 2 4 5
+8 6 4 4 1
+1 3 6 7 9

examples/aoc2024/day03/part1.jou

@@ -0,0 +1,56 @@
+import "stdlib/str.jou"
+import "stdlib/io.jou"
+import "stdlib/mem.jou"
+import "stdlib/ascii.jou"
+
+
+# Moves s in-place beyond used characters. Returns 0 on failure.
+def parse_int(s: byte**) -> int:
+    result = 0
+    while is_ascii_digit(**s):
+        result *= 10
+        result += (*(*s)++ - '0')
+    return result
+
+
+# Returns 0 if doesn't match.
+def parse_mul(s: byte*) -> int:
+    if not starts_with(s, "mul("):
+        return 0
+    s = &s[4]
+
+    a = parse_int(&s)
+    if *s++ != ',':
+        return 0
+    b = parse_int(&s)
+    if *s++ != ')':
+        return 0
+    return a*b
+
+
+def main() -> int:
+    max_size = 100000
+    big_string: byte* = malloc(max_size)
+
+    f = fopen("sampleinput1.txt", "r")
+    assert f != NULL
+
+    i = 0
+    while True:
+        c = fgetc(f)
+        EOF = -1  # TODO: belongs to stdlib
+        if c == EOF:
+            break
+        assert i < max_size
+        big_string[i++] = c as byte
+
+    fclose(f)
+
+    result = 0 as long
+    s = big_string
+    while *s != '\0':
+        result += parse_mul(s++)
+
+    free(big_string)
+    printf("%d\n", result)  # Output: 161
+    return 0

examples/aoc2024/day03/part2.jou

@@ -0,0 +1,74 @@
+import "stdlib/str.jou"
+import "stdlib/io.jou"
+import "stdlib/mem.jou"
+import "stdlib/ascii.jou"
+
+
+# Moves s in-place beyond used characters. Returns 0 on failure.
+def parse_int(s: byte**) -> int:
+    result = 0
+    while is_ascii_digit(**s):
+        result *= 10
+        result += (*(*s)++ - '0')
+    return result
+
+
+# Returns 0 if doesn't match.
+def parse_mul(s: byte*) -> int:
+    if not starts_with(s, "mul("):
+        return 0
+    s = &s[4]
+
+    a = parse_int(&s)
+    if *s++ != ',':
+        return 0
+    b = parse_int(&s)
+    if *s++ != ')':
+        return 0
+    return a*b
+
+
+def remove_disabled_sections(s: byte*) -> None:
+    while True:
+        dont = strstr(s, "don't()")
+        if dont == NULL:
+            break
+
+        do = strstr(dont, "do()")
+        if do == NULL:
+            # disable to end
+            *dont = '\0'
+        else:
+            # delete dont()...do()
+            do_end = &do[4]
+            memmove(dont, do_end, strlen(do_end) + 1)
+
+
+def main() -> int:
+    max_size = 100000
+    big_string: byte* = malloc(max_size)
+
+    f = fopen("sampleinput.txt", "r")
+    assert f != NULL
+
+    i = 0
+    while True:
+        c = fgetc(f)
+        EOF = -1  # TODO: belongs to stdlib
+        if c == EOF:
+            break
+        assert i < max_size
+        big_string[i++] = c as byte
+
+    fclose(f)
+
+    remove_disabled_sections(big_string)
+
+    result = 0 as long
+    s = big_string
+    while *s != '\0':
+        result += parse_mul(s++)
+
+    free(big_string)
+    printf("%d\n", result)  # Output: 48
+    return 0

examples/aoc2024/day03/sampleinput1.txt

@@ -0,0 +1 @@
+xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))

examples/aoc2024/day03/sampleinput2.txt

@@ -0,0 +1 @@
+xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))

examples/aoc2024/day04/part1.jou

@@ -0,0 +1,56 @@
+import "../grid.jou"
+import "stdlib/str.jou"
+import "stdlib/mem.jou"
+import "stdlib/io.jou"
+
+
+def count_in_string(s: byte*) -> int:
+    n = 0
+    for i = 0; s[i] != '\0'; i++:
+        if starts_with(&s[i], "XMAS") or starts_with(&s[i], "SAMX"):
+            n++
+    return n
+
+
+def count_diagonals(grid: Grid*) -> int:
+    big_size = grid->width + grid->height + 69
+    temp_string: byte* = malloc(big_size)
+    assert temp_string != NULL
+
+    result = 0
+
+    for c = -big_size; c <= big_size; c++:
+        # diagonals like /, along lines whose equation is y = x + c
+        p = temp_string
+        for x = 0; x < grid->width; x++:
+            y = x + c
+            if 0 <= y and y < grid->height:
+                *p++ = grid->get([x, y])
+        *p = '\0'
+        result += count_in_string(temp_string)
+
+        # diagonals like \, along lines whose equation is y = -x + c
+        p = temp_string
+        for x = 0; x < grid->width; x++:
+            y = -x + c
+            if 0 <= y and y < grid->height:
+                *p++ = grid->get([x, y])
+        *p = '\0'
+        result += count_in_string(temp_string)
+
+    free(temp_string)
+    return result
+
+
+def main() -> int:
+    f = fopen("sampleinput.txt", "r")
+    grid = read_grid_from_file(f)
+    fclose(f)
+
+    horizontal = count_in_string(grid.data)
+    grid.transpose()
+    vertical = count_in_string(grid.data)
+    diagonal = count_diagonals(&grid)
+    printf("%d\n", horizontal + vertical + diagonal)  # Output: 18
+
+    return 0

examples/aoc2024/day04/part2.jou

@@ -0,0 +1,46 @@
+import "../grid.jou"
+import "stdlib/io.jou"
+import "stdlib/mem.jou"
+
+
+# Count how many times template matches grid
+# "." in template can be any character
+def count_template(grid: Grid*, template: Grid*) -> int:
+    count = 0
+    for ox = 0; ox <= grid->width - template->width; ox++:
+        for oy = 0; oy <= grid->height - template->height; oy++:
+            all_match = True
+            for x = 0; x < template->width; x++:
+                for y = 0; y < template->height; y++:
+                    grid_byte = grid->get([ox + x, oy + y])
+                    template_byte = template->get([x, y])
+                    if grid_byte != template_byte and template_byte != '.':
+                        all_match = False
+            if all_match:
+                count += 1
+    return count
+
+
+def main() -> int:
+    templates: Grid[10]
+    num_templates = 0
+
+    f = fopen("part2_templates.txt", "r")
+    while feof(f) == 0:
+        assert num_templates < sizeof(templates)/sizeof(templates[0])
+        templates[num_templates++] = read_grid_from_file(f)
+    fclose(f)
+
+    f = fopen("sampleinput.txt", "r")
+    grid = read_grid_from_file(f)
+    fclose(f)
+
+    result = 0
+    for i = 0; i < num_templates; i++:
+        result += count_template(&grid, &templates[i])
+    printf("%d\n", result)  # Output: 9
+
+    for i = 0; i < num_templates; i++:
+        free(templates[i].data)
+
+    return 0