update leetcode

leetcode_rs/problems/p17/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "p17"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

leetcode_rs/problems/p17/src/main.rs

@@ -0,0 +1,45 @@
+fn letter_combinations(digits: String) -> Vec<String> {
+    if digits.is_empty() {
+        return vec![];
+    }
+    let alpha_set: Vec<Vec<char>> = vec![
+        vec![],                   // 0
+        vec![],                   // 1
+        vec!['a', 'b', 'c'],      // 2
+        vec!['d', 'e', 'f'],      // 3
+        vec!['g', 'h', 'i'],      // 4
+        vec!['j', 'k', 'l'],      // 5
+        vec!['m', 'n', 'o'],      // 6
+        vec!['p', 'q', 'r', 's'], // 7
+        vec!['t', 'u', 'v'],      // 8
+        vec!['w', 'x', 'y', 'z'], // 9
+    ];
+
+    let mut candidate_alpha = Vec::new();
+    for digit in digits.chars() {
+        let digit = digit.to_digit(10).unwrap() as usize;
+        candidate_alpha.push(alpha_set[digit].clone());
+    }
+
+    let total_len: usize = candidate_alpha.iter().map(|x| x.len()).product();
+    let mut result: Vec<String> = vec![String::new(); total_len];
+
+    for (idx, combination) in result.iter_mut().enumerate() {
+        let mut temp_idx = idx;
+        for chars in candidate_alpha.iter().rev() {
+            let char_idx = temp_idx % chars.len();
+            combination.push(chars[char_idx]);
+            temp_idx /= chars.len();
+        }
+        combination
+            .chars()
+            .rev()
+            .collect::<String>()
+            .clone_into(combination);
+    }
+
+    result
+}
+fn main() {
+    dbg!(letter_combinations("234".to_string()));
+}