1937_Maximum_Number_of_Points_with_Cost

Author: partho-maple

README.md

@@ -781,7 +781,9 @@ BFS, DFS, Dijkstra, Floyd–Warshall, Bellman-Ford, Kruskal, Prim's, Minimum Spa
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+|61| [1937. Maximum Number of Points with Cost](https://tinyurl.com/yhh6dmeh) | [Swift](https://tinyurl.com/wuja3c4/1937_Maximum_Number_of_Points_with_Cost.swift)| [Art 1](https://tinyurl.com/yg6hs4md) | Medium | --- |
+
 
 
 </p>

leetcode.com/swift/DS_ALGO_PRAC.playground/Sources/swift/1937_Maximum_Number_of_Points_with_Cost.swift

@@ -0,0 +1,54 @@
+// Brute force
+class Solution {
+    func maxPoints(_ points: [[Int]]) -> Int {
+        guard points.count > 1 else {
+            return points[0].max()!
+        }
+        var (prevRowDP, currentRowDP) = (points[0], Array(repeating: Int.min, count: points[0].count))
+        for row in 1..<points.count {
+            for col in 0..<points[0].count {
+                for prevCol in 0..<prevRowDP.count {
+                    currentRowDP[col] = [currentRowDP[col], points[row][col] + prevRowDP[prevCol] - abs(col - prevCol)].max()!
+                }
+            }
+            prevRowDP = currentRowDP
+        }
+        return currentRowDP.max()!
+    }
+}
+
+// DP. Main algorithm from here, https://tinyurl.com/yg6hs4md
+class Solution {
+    func maxPoints(_ points: [[Int]]) -> Int {
+        if points.count == 1 {
+            return points[0].max()!
+        }
+        if points[0].count == 1 {
+            return points.compactMap { $0.reduce(0, +) }.reduce(0, +)
+        }
+        
+        var prevRowDP = points[0]
+        for row in 0..<points.count - 1 {
+            var currentRowDP = Array(repeating: 0, count: points[0].count)
+
+            // Build left
+            var left = [prevRowDP[0]] + Array(repeating: 0, count: prevRowDP.count - 1)
+            for index in 1..<left.count {
+                left[index] = [prevRowDP[index], left[index - 1] - 1].max()!
+            }
+            
+            // Build right
+            var right = Array(repeating: 0, count: prevRowDP.count - 1) + [prevRowDP.last!]
+            for index in stride(from: right.count - 2, through: 0, by: -1) {
+                right[index] = [prevRowDP[index], right[index + 1] - 1].max()!
+            }
+            
+            
+            for col in 0..<prevRowDP.count {
+                currentRowDP[col] = [left[col], right[col]].max()! + points[row + 1][col]
+            }
+            prevRowDP = currentRowDP
+        }
+        return prevRowDP.max()!
+    }
+}