[Array] Add a solution to Game of Lift

Author: Yi Gu

Array/GameLife.swift

@@ -0,0 +1,53 @@
+/**
+ * Question Link: https://leetcode.com/problems/game-of-life/
+ * Primary idea: Divide whole things to 4 cases, change 1 to 2 and 0 to 3 to avoid 
+ *               overrite issues, and then use %2 to get final results
+ *
+ * Time Complexity: O(n), Space Complexity: O(1)
+ *
+ */
+
+class GameLife {
+    func gameOfLife(_ board: inout [[Int]]) {
+        guard board.count > 0 else {
+            return
+        }
+    
+        let m = board.count, n = board[0].count
+        
+        for i in 0 ..< m {
+            for j in 0 ..< n {
+                changeStatus(&board, i, j, m, n)
+            }
+        }
+        
+        board = board.map { $0.map { $0 % 2 } }
+    }
+    
+    private func changeStatus(_ board: inout [[Int]], _ i: Int, _ j: Int, _ m: Int, _ n: Int) {
+        var liveNum = 0
+    
+        for x in i - 1 ... i + 1 {
+            for y in j - 1 ... j + 1 {
+                if x < 0 || x >= m || y < 0 || y >= n {
+                    continue
+                }
+                if x == i && y == j {
+                    continue
+                }
+                
+                liveNum = board[x][y] == 1 || board[x][y] == 2 ? liveNum + 1 : liveNum
+            }
+        }
+        
+        if board[i][j] == 1 {
+            if liveNum < 2 || liveNum > 3 {
+                board[i][j] = 2
+            }
+        } else {
+            if liveNum == 3 {
+                board[i][j] = 3
+            }
+        }
+    }
+}