g2501_2600.s2559_count_vowel_strings_in_ranges.Solution Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of leetcode-in-java21 Show documentation

Java-based LeetCode algorithm problem solutions, regularly updated

There is a newer version: 1.38

package g2501_2600.s2559_count_vowel_strings_in_ranges;

// #Medium #Array #String #Prefix_Sum #2023_08_19_Time_4_ms_(99.59%)_Space_85.6_MB_(78.46%)

/**
 * 2559 - Count Vowel Strings in Ranges\.
 *
 * Medium
 *
 * You are given a **0-indexed** array of strings `words` and a 2D array of integers `queries`.
 *
 * Each query queries[i] = [l_i, r_i] asks us to find the number of strings present in the range l_i to r_i (both **inclusive** ) of `words` that start and end with a vowel.
 *
 * Return _an array_ `ans` _of size_ `queries.length`_, where_ `ans[i]` _is the answer to the_ `i`^th _query_.
 *
 * **Note** that the vowel letters are `'a'`, `'e'`, `'i'`, `'o'`, and `'u'`.
 *
 * **Example 1:**
 *
 * **Input:** words = ["aba","bcb","ece","aa","e"], queries = \[\[0,2],[1,4],[1,1]]
 *
 * **Output:** [2,3,0]
 *
 * **Explanation:** The strings starting and ending with a vowel are "aba", "ece", "aa" and "e". 
 *
 * The answer to the query [0,2] is 2 (strings "aba" and "ece"). 
 *
 * to query [1,4] is 3 (strings "ece", "aa", "e"). 
 *
 * to query [1,1] is 0. 
 *
 * We return [2,3,0].
 *
 * **Example 2:**
 *
 * **Input:** words = ["a","e","i"], queries = \[\[0,2],[0,1],[2,2]]
 *
 * **Output:** [3,2,1]
 *
 * **Explanation:** Every string satisfies the conditions, so we return [3,2,1].
 *
 * **Constraints:**
 *
 * *   1 <= words.length <= 10⁵
 * *   `1 <= words[i].length <= 40`
 * *   `words[i]` consists only of lowercase English letters.
 * *   sum(words[i].length) <= 3 * 10⁵
 * *   1 <= queries.length <= 10⁵
 * *   0 <= l_i <= r_i < words.length
**/
public class Solution {
    private boolean validWord(String s) {
        char cStart = s.charAt(0);
        char cEnd = s.charAt(s.length() - 1);
        boolean flag1 =
                cStart == 'a' || cStart == 'e' || cStart == 'i' || cStart == 'o' || cStart == 'u';
        boolean flag2 = cEnd == 'a' || cEnd == 'e' || cEnd == 'i' || cEnd == 'o' || cEnd == 'u';
        return flag1 && flag2;
    }

    public int[] vowelStrings(String[] words, int[][] queries) {
        int[] prefixArr = new int[words.length];
        prefixArr[0] = validWord(words[0]) ? 1 : 0;
        for (int i = 1; i < words.length; ++i) {
            if (validWord(words[i])) {
                prefixArr[i] = prefixArr[i - 1] + 1;
            } else {
                prefixArr[i] = prefixArr[i - 1];
            }
        }
        int[] res = new int[queries.length];
        for (int i = 0; i < queries.length; ++i) {
            int upperBound = queries[i][1];
            int lowerBound = queries[i][0];
            int val =
                    (lowerBound == 0)
                            ? prefixArr[upperBound]
                            : prefixArr[upperBound] - prefixArr[lowerBound - 1];
            res[i] = val;
        }
        return res;
    }
}