Merge pull request youngyangyang04#2406 from fwqaaq/patch-3

Update 0695.岛屿的最大面积.md for go

Author: youngyangyang04

problems/0695.岛屿的最大面积.md

@@ -428,6 +428,146 @@ var maxAreaOfIsland = function (grid) {
 };
 ```
 
+### Go
+
+dsf: 版本一
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+var count int = 0
+
+func maxAreaOfIsland(grid [][]int) int {
+	res := 0
+	visited := make([][]bool, len(grid))
+	for i := 0; i < len(grid); i++ {
+		visited[i] = make([]bool, len(grid[0]))
+	}
+
+	for i, rows := range grid {
+		for j, v := range rows {
+			if v == 1 && !visited[i][j] {
+				// 第一种写法，重制 count，必定有 1 个
+				count = 1
+				dfs(grid, visited, i, j)
+				res = max(res, count)
+			}
+
+		}
+	}
+
+	return res
+}
+
+// 第一种写法
+func dfs(grid [][]int, visited [][]bool, i, j int) {
+	visited[i][j] = true // 标记已访问，循环中未标记会导致重复
+	for _, d := range DIRECTIONS {
+		x, y := i+d[0], j+d[1]
+		if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
+			continue
+		}
+		if grid[x][y] == 1 && !visited[x][y] {
+			count++
+			dfs(grid, visited, x, y)
+		}
+	}
+}
+```
+
+dfs：版本二
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+var count int = 0
+
+func maxAreaOfIsland(grid [][]int) int {
+	res := 0
+	visited := make([][]bool, len(grid))
+	for i := 0; i < len(grid); i++ {
+		visited[i] = make([]bool, len(grid[0]))
+	}
+
+	for i, rows := range grid {
+		for j, v := range rows {
+			if v == 1 && !visited[i][j] {
+				// 第二种写法
+				count = 0
+				dfs(grid, visited, i, j)
+				res = max(res, count)
+			}
+
+		}
+	}
+
+	return res
+}
+
+// 第二种写法
+func dfs(grid [][]int, visited [][]bool, i, j int) {
+	if visited[i][j] || grid[i][j] == 0 {
+		return
+	}
+	visited[i][j] = true
+	count++
+	for _, d := range DIRECTIONS {
+		x, y := i+d[0], j+d[1]
+		if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
+			continue
+		}
+		dfs(grid, visited, x, y)
+	}
+}
+```
+
+bfs:
+
+```go
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+var count int = 0
+
+func maxAreaOfIsland(grid [][]int) int {
+	res := 0
+	visited := make([][]bool, len(grid))
+	for i := 0; i < len(grid); i++ {
+		visited[i] = make([]bool, len(grid[0]))
+	}
+
+	for i, rows := range grid {
+		for j, v := range rows {
+			if v == 1 && !visited[i][j] {
+				count = 0
+				bfs(grid, visited, i, j)
+				res = max(res, count)
+			}
+
+		}
+	}
+
+	return res
+}
+
+// bfs
+func bfs(grid [][]int, visited [][]bool, i, j int) {
+	visited[i][j] = true
+	count++
+	queue := [][2]int{{i, j}}
+	for len(queue) > 0 {
+		cur := queue[0]
+		queue = queue[1:]
+		for _, d := range DIRECTIONS {
+			x, y := cur[0]+d[0], cur[1]+d[1]
+			if x < 0 || x >= len(grid) || y < 0 || y >= len(grid[0]) {
+				continue
+			}
+			if grid[x][y] == 1 && !visited[x][y] {
+				count++
+				queue = append(queue, [2]int{x, y})
+				visited[x][y] = true
+			}
+		}
+	}
+}
+```
 
 ### Rust