1138_Alphabet_Board_Path

Author: partho-maple

README.md

@@ -613,6 +613,7 @@ BFS, DFS, Dijkstra, Floyd–Warshall, Bellman-Ford, Kruskal, Prim's, Minimum Spa
 |47| [1245. Tree Diameter](https://tinyurl.com/yxq4uykv) | [Python](https://tinyurl.com/wu6rdaw/1245_Tree_Diameter.py), [Swift](https://tinyurl.com/wuja3c4/1245_Tree_Diameter.swift) | [Art 1](https://www.geeksforgeeks.org/longest-path-undirected-tree/) | Medium |📌 Learned, 2 BFS. Important and interesting |
 |48| [1376. Time Needed to Inform All Employees](https://tinyurl.com/y3e5bb22) | [Python](https://tinyurl.com/wu6rdaw/1376_Time_Needed_to_Inform_All_Employees.py), [Swift](https://tinyurl.com/wuja3c4/1376_Time_Needed_to_Inform_All_Employees.swift) | [Art 1](https://tinyurl.com/y2lw6s4j) | Medium |📌 BFS, DFS |
 |49| [286. Walls and Gates](https://tinyurl.com/y3ollzsl) | [Python](https://tinyurl.com/wu6rdaw/286_Walls_and_Gates.py), [Swift](https://tinyurl.com/wuja3c4/286_Walls_and_Gates.swift) | --- | Medium |📌 BFS, DFS |
+|50| [286. Walls and Gates](https://tinyurl.com/y2xk6r98) | [Python](https://tinyurl.com/wu6rdaw/1138_Alphabet_Board_Path.py), [Swift](https://tinyurl.com/wuja3c4/1138_Alphabet_Board_Path.swift) | --- | Medium |📌 BFS |
 
 
 </p>

leetcode.com/swift/DS_ALGO_PRAC.playground/Sources/swift/1138_Alphabet_Board_Path.swift

@@ -0,0 +1,55 @@
+import Foundation
+class Solution {
+    func alphabetBoardPath(_ target: String) -> String {
+
+        let board_array = ["abcde", "fghij", "klmno", "pqrst", "uvwxy", "z"]
+            .map { Array($0)
+                .map { String($0) } }
+        
+        let target_array = Array(target)
+            .map { String($0) }
+        
+        var current_target_index = 0
+        var queue = [(Int, Int, String)]()
+        var visitedSet = Set<String>()
+        var result = ""
+        
+        queue.append((0, 0, ""))
+        visitedSet.insert(board_array[0][0])
+        
+        while queue.isEmpty == false {
+            var (row, col, path) = queue.removeFirst()
+            
+            if board_array[row][col] == target_array[current_target_index] {
+
+                path += "!"
+                current_target_index += 1
+                visitedSet.removeAll()
+                queue.removeAll()
+                visitedSet.insert(board_array[row][col])
+                queue.append((row, col, path))
+                
+                if current_target_index >= target_array.count {
+                    result = path
+                    break
+                } else {
+                    continue
+                }
+            }
+            
+            for neighbor in [ (-1,0,"U"), (0,1,"R"), (1,0,"D"), (0,-1,"L") ] {
+                let (new_row, new_col, direction) = (row + neighbor.0, col + neighbor.1, neighbor.2)
+                if new_row < board_array.count &&
+                    new_row >= 0 &&
+                    new_col < board_array[new_row].count &&
+                    new_col >= 0 &&
+                    !visitedSet.contains(board_array[new_row][new_col]) {
+                        
+                        visitedSet.insert(board_array[new_row][new_col])
+                        queue.append((new_row, new_col, path + direction))
+                }
+            }
+        }
+        return result
+    }
+}