init

problems/p17/Cargo.toml

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+[package]
+name = "p17"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

problems/p17/src/main.rs

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+fn number_to_letters(n: u32) -> String {
+    if n == 0 {
+        return "zero".to_string();
+    }
+
+    let ones = [
+        "", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine",
+    ];
+    let teens = [
+        "ten",
+        "eleven",
+        "twelve",
+        "thirteen",
+        "fourteen",
+        "fifteen",
+        "sixteen",
+        "seventeen",
+        "eighteen",
+        "nineteen",
+    ];
+    let tens = [
+        "", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety",
+    ];
+
+    let mut result = String::new();
+    let mut num = n;
+
+    // 处理千位
+    if num >= 1000 {
+        let thousands = num / 1000;
+        result.push_str(&number_to_letters_under_1000(
+            thousands, &ones, &teens, &tens,
+        ));
+        result.push_str("thousand");
+        num %= 1000;
+        if num > 0 {
+            result.push_str("and");
+        }
+    }
+
+    // 处理百位以下
+    if num > 0 {
+        result.push_str(&number_to_letters_under_1000(num, &ones, &teens, &tens));
+    }
+
+    result
+}
+
+fn number_to_letters_under_1000(n: u32, ones: &[&str], teens: &[&str], tens: &[&str]) -> String {
+    let mut result = String::new();
+    let mut num = n;
+
+    // 处理百位
+    if num >= 100 {
+        let hundreds = num / 100;
+        result.push_str(ones[hundreds as usize]);
+        result.push_str("hundred");
+        num %= 100;
+        if num > 0 {
+            result.push_str("and");
+        }
+    }
+
+    // 处理十位和个位
+    if num >= 20 {
+        let ten_digit = num / 10;
+        result.push_str(tens[ten_digit as usize]);
+        num %= 10;
+        if num > 0 {
+            result.push_str(ones[num as usize]);
+        }
+    } else if num >= 10 {
+        result.push_str(teens[(num - 10) as usize]);
+    } else if num > 0 {
+        result.push_str(ones[num as usize]);
+    }
+
+    result
+}
+
+fn count_letters(text: &str) -> usize {
+    text.chars().filter(|c| c.is_alphabetic()).count()
+}
+
+fn solve_letter_count(start: u32, end: u32) -> usize {
+    (start..=end)
+        .map(|n| count_letters(&number_to_letters(n)))
+        .sum()
+}
+
+fn main() {
+    // 验证 1-5 的例子
+    let test_words = ["one", "two", "three", "four", "five"];
+    let test_count: usize = test_words.iter().map(|w| w.len()).sum();
+    println!("1到5的字母数: {test_count}");
+
+    // 验证我们的函数
+    let our_count = solve_letter_count(1, 5);
+    println!("我们函数计算的1到5: {our_count}");
+
+    // 计算 1 到 1000
+    let result = solve_letter_count(1, 1000);
+    println!("1到1000的字母总数: {result}");
+}