Add solution 733

Author: vulgur

733_FloodFill.swift

@@ -0,0 +1,29 @@
+class Solution {
+    func floodFill(_ image: [[Int]], _ sr: Int, _ sc: Int, _ newColor: Int) -> [[Int]] {
+        var visited = Array(repeating:Array(repeating: false, count:image[0].count), count:image.count)
+        var result = image
+        if sr<0 || sr>image.count-1 || sc<0 || sc>image[0].count-1 {
+            return image
+        }
+        let oldColor = image[sr][sc]
+        if oldColor != newColor {
+            fill(&result, sr, sc, oldColor, newColor, &visited)
+            return result
+        } else {
+            return image
+        }
+        
+    }
+    
+    func fill(_ result: inout [[Int]], _ sr: Int, _ sc: Int, _ color: Int, _ newColor: Int, _ visited: inout [[Bool]]) {
+        guard sr>=0, sr<result.count, sc>=0, sc<result[0].count, visited[sr][sc]==false, result[sr][sc]==color else {
+            return
+        }
+        visited[sr][sc] = true
+        result[sr][sc] = newColor
+        fill(&result, sr-1, sc, color, newColor, &visited)
+        fill(&result, sr+1, sc, color, newColor, &visited)
+        fill(&result, sr, sc-1, color, newColor, &visited)
+        fill(&result, sr, sc+1, color, newColor, &visited)
+    }
+}