Day1

.gitignore

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+**/target

day1/c/day1.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define LINE_MAX 64
+#define LIST_MAX 1024
+#define abs(a) (a) < 0 ? -(a) : (a);
+
+int cmp(const void*, const void*);
+
+int main() {
+    char *p, *buf, c;
+    int left, right, *left_list, *right_list, i = 0;
+
+    buf = calloc(LINE_MAX, sizeof(char));
+    p = buf;
+    left_list = calloc(LIST_MAX, sizeof(*left_list));
+    right_list = calloc(LIST_MAX, sizeof(*right_list));
+
+    while ((c = getchar()) != EOF) {
+        *p++ = c;
+        if (c == '\n') {
+            *p = '\0';
+            sscanf(buf, "%i %i", &left, &right);
+            left_list[i] = left;
+            right_list[i] = right;
+            i++;
+            memset(buf, 0, LINE_MAX);
+            p = buf;
+        }
+    }
+
+    free(buf);
+
+    qsort(left_list, i, sizeof(*left_list), cmp);
+    qsort(right_list, i, sizeof(*right_list), cmp);
+
+    int sum = 0;
+    for (int j = 0; j < i; j++) {
+        sum += abs(left_list[j] - right_list[j]);
+    }
+
+    int similarity = 0;
+
+    for (int j = 0; j < i; j++) {
+        int count = 0;
+        for (int k = 0; k < i; k++) {
+            if (left_list[j] == right_list[k]) {
+                count++;
+            }
+        }
+        similarity += left_list[j] * count;
+    }
+
+    free(left_list);
+    free(right_list);
+
+    printf("%i\n", sum);
+    printf("%i\n", similarity);
+}
+
+int cmp(const void* a, const void* b) {
+    return *(int*)a - *(int*)b;
+}

day1/rust/Cargo.lock

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+# 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",
+]

day1/rust/Cargo.toml

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+[package]
+name = "rust"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+itertools = "0.13.0"

day1/rust/src/main.rs

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+use itertools::Itertools;
+
+fn main() {
+    let stdin = std::io::stdin();
+
+    let mut left_list = Vec::new();
+    let mut right_list = Vec::new();
+
+    for line in stdin.lines() {
+        let line = line.unwrap();
+
+        let (left, right) = line
+            .split_whitespace()
+            .map(|e| e.parse::<isize>().unwrap())
+            .collect_tuple()
+            .unwrap();
+
+        left_list.push(left);
+        right_list.push(right);
+    }
+
+    left_list.sort();
+    right_list.sort();
+
+    let distance: isize = left_list
+        .iter()
+        .zip(&right_list)
+        .map(|(left, right)| left - right)
+        .map(|e| e.abs())
+        .sum();
+
+    println!("{}", distance);
+
+    let similarity: usize = left_list
+        .iter()
+        .map(|e| usize::try_from(*e).unwrap() * right_list.iter().filter(|n| *n == e).count())
+        .sum();
+
+    println!("{}", similarity);
+}

day1/sample.txt

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+3   4
+4   3
+2   5
+1   3
+3   9
+3   3