1170. Compare Strings by Frequency of the Smallest Character

Let the function f(s) be the frequency of the lexicographically smallest character in a non-empty string s. For example, if s = "dcce" then f(s) = 2 because the lexicographically smallest character is 'c', which has a frequency of 2.

You are given an array of strings words and another array of query strings queries. For each query queries[i], count the number of words in words such that f(queries[i]) < f(W) for each W in words.

Return an integer array answer, where each answer[i] is the answer to the ith query.

 

Example 1:

Input: queries = ["cbd"], words = ["zaaaz"]
Output: [1]
Explanation: On the first query we have f("cbd") = 1, f("zaaaz") = 3 so f("cbd") < f("zaaaz").

Example 2:

Input: queries = ["bbb","cc"], words = ["a","aa","aaa","aaaa"]
Output: [1,2]
Explanation: On the first query only f("bbb") < f("aaaa"). On the second query both f("aaa") and f("aaaa") are both > f("cc").

 

Constraints:

  • 1 <= queries.length <= 2000
  • 1 <= words.length <= 2000
  • 1 <= queries[i].length, words[i].length <= 10
  • queries[i][j], words[i][j] consist of lowercase English letters.

Rust Solution

struct Solution;

impl Solution {
    fn f(s: &str) -> usize {
        let mut count = vec![0; 26];
        let mut min = b'z';
        for b in s.bytes() {
            min = min.min(b);
            count[(b - b'a') as usize] += 1;
        }
        count[(min - b'a') as usize]
    }
    fn num_smaller_by_frequency(queries: Vec<String>, words: Vec<String>) -> Vec<i32> {
        let f_queries: Vec<usize> = queries.iter().map(|s| Self::f(s)).collect();
        let f_words: Vec<usize> = words.iter().map(|s| Self::f(s)).collect();
        let mut counts = vec![0; 12];
        for f in f_words {
            counts[f] += 1;
        }
        for i in (1..10).rev() {
            counts[i] += counts[i + 1];
        }
        f_queries.into_iter().map(|f| counts[f + 1]).collect()
    }
}

#[test]
fn test() {
    let queries = vec_string!["cbd"];
    let words = vec_string!["zaaaz"];
    let res = vec![1];
    assert_eq!(Solution::num_smaller_by_frequency(queries, words), res);
    let queries = vec_string!["bbb", "cc"];
    let words = vec_string!["a", "aa", "aaa", "aaaa"];
    let res = vec![1, 2];
    assert_eq!(Solution::num_smaller_by_frequency(queries, words), res);
}

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