Update 0695 solution

Author: halfrost

website/content/ChapterFour/0600~0699/0695.Max-Area-of-Island.md

@@ -45,6 +45,14 @@ Given the above grid, return`0`.
 ## 代码
 
 ```go
+
+var dir = [][]int{
+	{-1, 0},
+	{0, 1},
+	{1, 0},
+	{0, -1},
+}
+
 func maxAreaOfIsland(grid [][]int) int {
 	res := 0
 	for i, row := range grid {
@@ -61,6 +69,10 @@ func maxAreaOfIsland(grid [][]int) int {
 	return res
 }
 
+func isInGrid(grid [][]int, x, y int) bool {
+	return x >= 0 && x < len(grid) && y >= 0 && y < len(grid[0])
+}
+
 func areaOfIsland(grid [][]int, x, y int) int {
 	if !isInGrid(grid, x, y) || grid[x][y] == 0 {
 		return 0
@@ -74,6 +86,7 @@ func areaOfIsland(grid [][]int, x, y int) int {
 	}
 	return total
 }
+
 ```