Ex 1.1 2025

Author: FPG-992

2025/1st_set/contracts.txt

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+2 2
+5 3
+10 9
+6 1
+2 2

2025/1st_set/map1.txt

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+10
+0 1 2 0 1 2 0 1 3 1

2025/1st_set/map2.txt

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+10
+0 1 3 0 1 2 0 1 3 1

2025/1st_set/rain.sml

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+(* gia kathe thesi i,
+sthn arxh: gnwrizume pws den mporei na exei nero an aristera tou den uparxei hill
+efoson uparxei aristera tou hill, to i den mporei na einai megalutero apo to aristero kai deksi hill giati tha uparxei uperxilish.
+uparxei h periptwsh na exw aristera ena hill, deksia ena hill to opoio na einai iso h mikrotero apo to aristero kai na uparxei ena deksia 
+>= apo ta aristerotero hill, opote na dhmiourgeitai mia "limnh" opou uparxei ena hill to opoio exei nero apo panw tou, deksia h kai aristera tou
+
+pairnoume ena sequence apo N hills kai ta antistoixa height tous, opou stis koilades tous anamesa uparxei nero
+thelume ton ogko tou nerou anamesa sta hills
+
+sto position i, o ogkos tou nerou einai max to min height tou aristera kai deksia tou hill.
+
+water = max(0,min(Left[i], Right[i]) - Height[i])
+
+LeftHillI einai to hill me to megalutero height apo to i kai aristera tou
+RightHillI einai to hill me to megalutero height apo to i kai deksia tou
+ *)
+
+(* grafoume thn sunarthsh pou gia kathe position i, tha vriskei to max aristero tou *)
+fun MaxHillLeft hs =
+    let
+        fun loop ([], _, acc) = List.rev acc
+            | loop (h::t, m, acc) =
+                let
+                    val m' = Int.max(h, m) (* to megalutero height apo ta duo *)
+                in 
+                    loop(t, m', m'::acc)
+                end
+    in
+        loop (hs, 0, [])
+    end
+
+(* grafoume thn sunarthsh pou gia kathe position i, tha vriskei to max deksio tou *)
+fun MaxHillRight hs =
+    let
+        val revHS = List.rev hs
+        fun loop ([], _, acc) = acc
+            | loop (h::t, m, acc) =
+                let
+                    val m' = Int.max(h, m) (* to megalutero height apo ta duo *)
+                in 
+                    loop(t, m', m'::acc)
+                end
+    in
+        loop (revHS, 0, [])
+    end            
+
+fun WaterTrapped ([],[],[]) total = total
+    | WaterTrapped (h::hs, l::ls, r::rs) total =
+        let 
+            val water= Int.max(0, Int.min(l, r) - h) (* to water pou uparxei sto i *)
+        in 
+            WaterTrapped (hs, ls, rs) (total + water) (* prosthetoume to water sto total *)
+        end
+    | WaterTrapped _ _ = raise Fail "WaterTrapped: Invalid input"
+
+fun WaterTrappedMain hs =
+    let 
+        val leftHills = MaxHillLeft hs (* vriskei ta max aristera hills *)
+        val rightHills = MaxHillRight hs (* vriskei ta max deksia hills *)
+    in
+        WaterTrapped (hs, leftHills, rightHills) 0 (* ypologizei to water pou uparxei *)
+    end
+        
+fun readInts ins =
+  let
+    val line = valOf (TextIO.inputLine ins)
+    val toks = String.tokens Char.isSpace line
+  in
+    List.mapPartial Int.fromString toks
+  end
+
+
+fun rain filename =
+  let
+    val ins     = TextIO.openIn filename
+    val _       = TextIO.inputLine ins
+    val heights = readInts ins
+    val ()      = TextIO.closeIn ins
+    val result  = WaterTrappedMain heights
+  in
+    print (Int.toString result ^ "\n")
+  end