Merge pull request neetcode-gh#2145 from nirajvenkat/patch-15

Create 0017-letter-combinations-of-a-phone-number.rs

rust/0017-letter-combinations-of-a-phone-number.rs

@@ -0,0 +1,37 @@
+use std::collections::HashMap;
+
+impl Solution {
+ fn backtrack(i: usize, curr_str: String, result: &mut Vec<String>, digits: &String, d_c_map: &HashMap<char, &str>) {
+ if curr_str.len() == digits.len() {
+ result.push(curr_str);
+ return;
+ }
+
+ let letters = d_c_map.get(&digits.chars().nth(i).unwrap()).unwrap().to_string();
+ for ch in letters.chars() {
+ let mut append_str = curr_str.clone();
+ append_str.push(ch);
+ Self::backtrack(i + 1, append_str, result, digits, d_c_map);
+ }
+ }
+
+ pub fn letter_combinations(digits: String) -> Vec<String> {
+ let mut result = vec![];
+ let d_c_map = HashMap::from([
+ ('2', "abc"),
+ ('3', "def"),
+ ('4', "ghi"),
+ ('5', "jkl"),
+ ('6', "mno"),
+ ('7', "qprs"),
+ ('8', "tuv"),
+ ('9', "wxyz"),
+ ]);
+
+ if !digits.is_empty() {
+ Solution::backtrack(0, "".to_string(), &mut result, &digits, &d_c_map);
+ }
+
+ result
+ }
+}