Create 0983-minimum-cost-for-tickets.kt

Author: a93a

Diff for: kotlin/0983-minimum-cost-for-tickets.kt

@@ -0,0 +1,53 @@
+/*
+* DP without a DFS
+*/
+class Solution {
+    fun mincostTickets(days: IntArray, costs: IntArray): Int {
+        val dp = IntArray(days.size) {-1}
+        val zipped = intArrayOf(1,7,30).zip(costs)
+
+        for (i in days.lastIndex downTo 0) {
+            dp[i] = Integer.MAX_VALUE
+            for ((day, cost) in zipped) {
+                var next = i
+                while (next < days.size && days[next] < days[i] + day) next++
+                dp[i] = minOf(
+                    dp[i], 
+                    cost + if(next < days.size) dp[next] else 0
+                )
+            }
+        }
+        
+        return dp[0]
+    }
+}
+
+/*
+* DFS + cache
+*/
+class Solution {
+    fun mincostTickets(days: IntArray, costs: IntArray): Int {
+        val cache = IntArray(days.size) {-1}
+        val zipped = intArrayOf(1,7,30).zip(costs)
+
+        fun dfs(i: Int): Int {
+            if (i == days.size)
+                return 0
+
+            if (cache[i] != -1)
+                return cache[i]
+
+            cache[i] = Integer.MAX_VALUE
+            for ((day, cost) in zipped) {
+                var next = i
+                while (next < days.size && days[next] < days[i] + day)
+                    next++
+                cache[i] = minOf(cache[i], cost + dfs(next))
+            }
+
+            return cache[i]
+        }
+
+        return dfs(0)
+    }
+}