42

src/euler42/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "euler42"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

src/euler42/src/main.rs

@@ -0,0 +1,46 @@
+use std::{
+    fs::{self},
+    vec,
+};
+
+fn main() {
+    let content = read_file();
+    let triangle_numbers = generate_triangle_numbers();
+    let mut triangle_word_count = 0;
+    for value in &content {
+        if triangle_numbers.contains(value) {
+            triangle_word_count += 1;
+        }
+    }
+    println!("{triangle_word_count}");
+}
+
+fn read_file() -> Vec<usize> {
+    let s = fs::read_to_string("0042_words.txt").unwrap();
+    s.split(',')
+        .map(|s| s.to_string())
+        .map(|s| {
+            s.chars()
+                .skip(1)
+                .take_while(|c| c.is_ascii_uppercase())
+                .map(char_to_value)
+                .sum()
+        })
+        .collect()
+}
+
+fn char_to_value(c: char) -> usize {
+    c as usize - 64
+}
+
+fn generate_triangle_numbers() -> Vec<usize> {
+    let mut result = vec![];
+    for n in 1..=30 {
+        result.push(triangle_number(n));
+    }
+    result
+}
+
+fn triangle_number(n: usize) -> usize {
+    n * (n + 1) / 2
+}