LeetCode in Kotlin

820. Short Encoding of Words

Medium

A valid encoding of an array of words is any reference string s and array of indices indices such that:

• words.length == indices.length
• The reference string s ends with the '#' character.
• For each index indices[i], the substring of s starting from indices[i] and up to (but not including) the next '#' character is equal to words[i].

Given an array of words, return the length of the shortest reference string s possible of any valid encoding of words.

Example 1:

Input: words = [“time”, “me”, “bell”]

Output: 10

Explanation: A valid encoding would be s = "time#bell#" and indices = [0, 2, 5].

words[0] = “time”, the substring of s starting from indices[0] = 0 to the next ‘#’ is underlined in “time#bell#”

words[1] = “me”, the substring of s starting from indices[1] = 2 to the next ‘#’ is underlined in “time#bell#”

words[2] = “bell”, the substring of s starting from indices[2] = 5 to the next ‘#’ is underlined in “time#bell#”

Example 2:

Input: words = [“t”]

Output: 2

Explanation: A valid encoding would be s = “t#” and indices = [0].

Constraints:

• 1 <= words.length <= 2000
• 1 <= words[i].length <= 7
• words[i] consists of only lowercase letters.

Solution

class Solution {
    private class Node {
        var nodes = arrayOfNulls<Node>(26)
    }

    private fun insert(node: Node, word: String): Boolean {
        var current: Node? = node
        val n = word.length
        var flag = false
        for (i in n - 1 downTo 0) {
            if (current!!.nodes[word[i].code - 'a'.code] == null) {
                current.nodes[word[i].code - 'a'.code] = Node()
                flag = true
            }
            current = current.nodes[word[i].code - 'a'.code]
        }
        return flag
    }

    fun minimumLengthEncoding(words: Array<String>): Int {
        var out = 0
        words.sortWith { a: String, b: String -> b.length - a.length }
        val node = Node()
        for (word in words) {
            if (insert(node, word)) {
                out += word.length + 1
            }
        }
        return out
    }
}

This site is open source. Improve this page.