LeetCode 1048. Longest String Chain

Problem Statement

use std::collections::HashMap;

impl Solution {
    pub fn longest_str_chain(words: Vec<String>) -> i32 {
        let (mut ans, mut w) = (0, words);
        w.sort_by_key(|x| x.len());
        let mut map = HashMap::new();

        for word in w {
            if map.contains_key(&word) {
                continue;
            }
            map.insert(word.clone(), 1);
            for i in 0..word.len() {
                let mut c = word.clone();
                c.remove(i);
                if map.contains_key(&c) &&
                    (*map.get(&c).unwrap() + 1 > *map.get(&word).unwrap()) {
                    map.insert(word.clone(), map.get(&c).unwrap() + 1);
                }
            }
            ans = std::cmp::max(ans, *map.get(&word).unwrap());
        }
        return ans;
    }
}