Index Pairs of a String

I’ve used Brute-force to solve this problem. Other people used Trie to solve but I’m not yet familiar with it.

class Solution {
    fun indexPairs(text: String, words: Array<String>): Array<IntArray> {
        var low = 0
        var high = low + 1
        
        var output = ArrayList<IntArray>()
        
        while(low < text.length){
            if(text.substring(low, high) in words){
                output.add(intArrayOf(low, high-1))
            }
            
            high++
            
            if(high > text.length) {
                low++
                high = low 
            }
        }
        
        return output.toTypedArray()
    }
}
Runtime: 260 ms, faster than 33.33% of Kotlin online submissions for Index Pairs of a String.
Memory Usage: 37.6 MB, less than 100.00% of Kotlin online submissions for Index Pairs of a String.