Day2

day2/c/day2.c

@@ -0,0 +1,80 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define CHARS_MAX 64
+#define MAX_LEVELS 16
+#define abs(a) ((a) < 0 ? (-(a)) : (a))
+
+int is_safe(int *levels, int level_count);
+
+int main() {
+    char *p, *buf, c;
+
+    buf = calloc(CHARS_MAX, sizeof(char));
+    p = buf;
+    int safes1 = 0, safes2 = 0;
+
+    int levels[MAX_LEVELS], level_count = 0;
+    while ((c = getchar()) != EOF) {
+        *p++ = c;
+        if (c != '\n') {
+            continue;
+        }
+        p = buf;
+        int level = 0;
+
+        p--;
+        do {
+            p++;
+            sscanf(p, "%i", &levels[level_count]);
+            level_count++;
+            while (*p != ' ' && *p != '\n') p++;
+        } while(*p != '\n');
+
+        if (is_safe(levels, level_count)) {
+            safes1++;
+        }
+
+        int new_levels[MAX_LEVELS];
+        for (int i = 0; i < level_count; i++) {
+            memcpy(new_levels, levels, level_count * sizeof(levels[0]));
+            for (int j = i; j < level_count - 1; j++) {
+                new_levels[j] = levels[j+1];
+            }
+
+            if (is_safe(new_levels, level_count - 1)) {
+                safes2++;
+                break;
+            }
+        }
+
+        memset(buf, 0, CHARS_MAX);
+        p = buf;
+        level_count = 0;
+    }
+
+    free(buf);
+
+    printf("%i\n", safes1);
+    printf("%i\n", safes2);
+}
+
+int is_safe(int *levels, int level_count) {
+    int diff = 0, safe = 1;
+    for (int i = 0; i < level_count; i++) {
+        if (i != 0) {
+            if (abs(levels[i] - levels[i-1]) < 1 || abs(levels[i] - levels[i-1]) > 3) {
+                safe = 0;
+            }
+
+            if ((levels[i] - levels[i-1]) * diff < 0) {
+                safe = 0;
+            }
+
+            diff = levels[i] - levels[i-1];
+        }
+    }
+
+    return safe;
+}

day2/rust/Cargo.lock

@@ -0,0 +1,25 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "either"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
+
+[[package]]
+name = "itertools"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "413ee7dfc52ee1a4949ceeb7dbc8a33f2d6c088194d9f922fb8318faf1f01186"
+dependencies = [
+ "either",
+]
+
+[[package]]
+name = "rust"
+version = "0.1.0"
+dependencies = [
+ "itertools",
+]

day2/rust/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "rust"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+itertools = "0.13.0"

day2/rust/src/main.rs

@@ -0,0 +1,48 @@
+use itertools::Itertools;
+
+fn main() {
+    let stdin = std::io::stdin();
+    let mut input = Vec::new();
+
+    for line in stdin.lines() {
+        let line = line.unwrap();
+
+        let levels: Vec<_> = line
+            .split_whitespace()
+            .map(|e| e.parse::<isize>().unwrap())
+            .collect();
+
+        input.push(levels);
+    }
+
+    println!("{}", input.iter().filter(|e| is_safe(e)).count());
+
+    println!(
+        "{}",
+        input
+            .iter()
+            .map(|levels| {
+                levels.iter().combinations(levels.len() - 1).any(|e| {
+                    let combination: Vec<_> = e.into_iter().copied().collect();
+                    is_safe(&combination)
+                })
+            })
+            .filter(|&e| e)
+            .count()
+    );
+}
+
+fn is_safe(levels: &Vec<isize>) -> bool {
+    if levels.len() < 2 {
+        return true;
+    }
+
+    let direction = levels[1] - levels[0];
+
+    return levels
+        .iter()
+        .tuple_windows()
+        .filter(|&(a, b)| (b - a).abs() < 1 || (b - a).abs() > 3 || (b - a) * direction < 0)
+        .count()
+        == 0;
+}

day2/sample.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