Update 0200.岛屿数量.深搜版.md

problems/0200.岛屿数量.深搜版.md

@@ -389,50 +389,41 @@ function numIslands(grid: string[][]): number {
 ### Go
 
 ```go
+
+var DIRECTIONS = [4][2]int{{-1, 0}, {0, -1}, {1, 0}, {0, 1}}
+
 func numIslands(grid [][]byte) int {
-    // 用1标记已访问
-    visited := make([][]int, len(grid))
-    for i := 0; i < len(visited); i++{
-        visited[i] = make([]int, len(grid[0]))
-    }
+	res := 0
 
-    var bfs func(x, y int)
-    bfs = func(x, y int){
-        stack := make([][]int, 0)
-        stack = append(stack, []int{x, y})
-        moveX := []int{1, -1, 0, 0}
-        moveY := []int{0, 0, 1, -1} 
+	visited := make([][]bool, len(grid))
+	for i := 0; i < len(grid); i++ {
+		visited[i] = make([]bool, len(grid[0]))
+	}
 
-        for len(stack) != 0{
-            node := stack[len(stack) - 1]
-            stack = stack[:len(stack) - 1]
+	for i, rows := range grid {
+		for j, v := range rows {
+			if v == '1' && !visited[i][j] {
+				res++
+				dfs(grid, visited, i, j)
+			}
+		}
+	}
 
-            for i := 0; i < 4; i++{
-                dx := moveX[i] + node[0]
-                dy := moveY[i] + node[1]
-                if dx < 0 || dx >= len(grid) || dy < 0 || dy >= len(grid[0]) || visited[dx][dy] == 1{
-                    continue
-                }
-                visited[dx][dy] = 1
-                if grid[dx][dy] == '1'{
-                    stack = append(stack, []int{dx,dy})
-                }
-            }
-        }
-    }
+	return res
+}
 
-    result := 0
-    for i := 0; i < len(grid); i++{
-        for j := 0; j < len(grid[0]); j++{
-            if visited[i][j] == 0 && grid[i][j] == '1'{
-                bfs(i, j)
-                visited[i][j] = 1
-                result++
-            }
-        }
-    }
+func dfs(grid [][]byte, visited [][]bool, i, j int) {
+	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] {
+			visited[x][y] = true
+			dfs(grid, visited, x, y)
+		}
+	}
 
-    return result
 }
 ```