Create 0139-word-break.kt

Author: a93a

kotlin/0139-word-break.kt

@@ -0,0 +1,17 @@
+class Solution {
+    fun wordBreak(s: String, wordDict: List<String>): Boolean {
+        val cache = BooleanArray(s.length+1)
+        cache[s.length] = true // lastPos is true, meaning [array of word length], lastPos] since string "" can be segmented of any list of any words (our dp basecase)
+        for(i in s.length-1 downTo 0){
+            for(word in wordDict){
+                if(word.length+i <= s.length){//enough chars in s for this word to be viable ?
+                    if(word == s.substring(i, i+word.length)){// its the same word char by char?
+                        if(cache[i+word.length] == true) //this cache index is true only if the cache at index [i+word.length is true]
+                            cache[i] = true
+                    }
+                }
+            }
+        }
+        return cache[0]
+    }
+}