Day1 Rust

day1/c/day1.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define LINE_MAX_LENGTH 256
+#define NUM_0_CHARCODE 48
+#define NUM_9_CHARCODE NUM_0_CHARCODE + 9
+#define PART_2 1
+#define FORWARD 1
+#define BACKWARD -1
+
+char* english_digit_strings[] = {
+    "zero",
+    "one",
+    "two",
+    "three",
+    "four",
+    "five",
+    "six",
+    "seven",
+    "eight",
+    "nine",
+};
+
+#define NUM_OF_DIGITS ((sizeof(english_digit_strings)) / (sizeof(english_digit_strings[0])))
+
+char *english_digit_strings_reversed[NUM_OF_DIGITS];
+
+int get_num(char *p, int dir) {
+    // Check whether it is a number
+    if (*p >= NUM_0_CHARCODE && *p <= NUM_9_CHARCODE) {
+        return *p - NUM_0_CHARCODE;
+    }
+
+    // Check spelled out numbers
+    if (PART_2) {
+        // Check each digit
+        for (int i = 0; i < NUM_OF_DIGITS; i++) {
+            char *reference = dir == FORWARD ? english_digit_strings[i] : english_digit_strings_reversed[i];
+            char *tmp = p;
+            int match = 1;
+            while (*reference != '\0') {
+                if (*tmp != *reference) {
+                    match = 0;
+                    break;
+                }
+                reference++;
+                tmp += dir;
+            }
+
+            if (match) {
+                return i;
+            }
+        }
+    }
+
+    return -1;
+}
+
+char* reverse_string(char* str) {
+    char *p = str;
+    while (*p != '\0') p++;
+
+    int len = p - str;
+
+    char *newstr = (char *)malloc(len + 1);
+    memset(newstr, 0, len + 1);
+    p--;
+
+
+    char* newp = newstr;
+    while (p != str) {
+        *newp = *p;
+        newp++;
+        p--;
+    }
+    *newp = *p;
+
+    return newstr;
+}
+
+void create_reversed_digit_strings() {
+    for (int i = 0; i < NUM_OF_DIGITS; i++) {
+        english_digit_strings_reversed[i] = reverse_string(english_digit_strings[i]);
+    }
+}
+
+int main() {
+    char *p, *buf, c;
+    int sum = 0, n = -1;
+    create_reversed_digit_strings();
+
+    buf = (char *)malloc(LINE_MAX_LENGTH);
+    memset(buf, 0, LINE_MAX_LENGTH);
+    p = buf;
+
+    while ((c = getchar()) != EOF) {
+        *p++ = c;
+        if (c == '\n') {
+            // Find last number (p points to the end of line)
+            while ((n = get_num(p, BACKWARD)) == -1) p--;
+            sum += n;
+            // Find first number
+            p = buf;
+            while ((n = get_num(p, FORWARD)) == -1) p++;
+            sum += n * 10;
+
+            memset(buf, 0, LINE_MAX_LENGTH);
+            p = buf;
+        }
+    }
+
+    free(buf);
+    for (int i = 0; i < NUM_OF_DIGITS; i++) {
+        free(english_digit_strings_reversed[i]);
+    }
+    printf("%i\n", sum);
+}

day1/rust/.gitignore

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+target

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 = "rust"
+version = "0.1.0"

day1/rust/Cargo.toml

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+[package]
+name = "rust"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day1/rust/src/main.rs

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+fn main() {
+    let part2 = true;
+    let english_digit_names = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"];
+
+
+    let stdin = std::io::stdin();
+    let mut sum = 0;
+
+    for line in stdin.lines() {
+        let line = line.unwrap();
+
+        let mut first: Option<u32> = None;
+        let mut last = 0;
+        for i in 0..line.chars().count() {
+            let slice = &line[i..];
+
+            let first_char = slice.chars().next().unwrap();
+            if first_char.is_digit(10) {
+                if first == None {
+                    first = first_char.to_digit(10);
+                }
+
+                last = first_char.to_digit(10).unwrap();
+            }
+
+            if part2 {
+                for (i, name) in english_digit_names.iter().enumerate() {
+                    if slice.starts_with(name) {
+                        if first == None {
+                            first = Some(i.try_into().unwrap());
+                        }
+
+                        last = i.try_into().unwrap();
+                    }
+                }
+            }
+        }
+
+        sum += first.unwrap() * 10;
+        sum += last;
+    }
+
+    println!("{}", sum);
+}

day1/sample.txt

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+1abc2
+pqr3stu8vwx
+a1b2c3d4e5f
+treb7uchet

day1/sample2.txt

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+two1nine
+eightwothree
+abcone2threexyz
+xtwone3four
+4nineeightseven2
+zoneight234
+7pqrstsixteen