Time: 76 ms (63.1%), Space: 55.6 MB (42.06%) - LeetHub

0130-surrounded-regions/0130-surrounded-regions.js

@@ -0,0 +1,55 @@
+/**
+ * @param {character[][]} board
+ * @return {void} Do not return anything, modify board in-place instead.
+ */
+var solve = function (board) {
+    let rows = board.length
+    let cols = board[0].length
+
+
+    var dfs = function (start, end) {
+        if (start < 0 || start >= rows || end < 0 || end >= cols || board[start][end] != "O") {
+            return
+        }
+        board[start][end] = "B"
+
+        for (let [r, c] of [[-1, 0], [1, 0], [0, -1], [0, 1]]) {
+            let x = r + start
+            let y = c + end
+            dfs(x, y)
+
+        }
+    }
+
+
+
+    // check all rows
+    for (let i = 0; i < rows; i++) {
+        if (board[i][0] == "O") {
+            dfs(i, 0)
+        }
+        if (board[i][cols - 1] == "O") {
+            dfs(i, cols - 1)
+        }
+    }
+    for (let i = 0; i < cols; i++) {
+        if (board[0][i] == "O") {
+            dfs(0, i)
+        }
+        if (board[rows - 1][i] == "O") {
+            dfs(rows - 1, i)
+        }
+    }
+
+    for (let i = 0; i < rows; i++) {
+        for (let j = 0; j < cols; j++) {
+            if (board[i][j] == "O") {
+                board[i][j] = "X"
+            }
+            else if (board[i][j] == 'B') {
+                board[i][j] = "O"
+            }
+        }
+    }
+    return board
+};