♻️ (mine-sweeper): refactor reveal with visited queue

Author: yuanyu90221

internal/game/game.go

@@ -173,36 +173,51 @@ func (board *Board) ToggleFlag(row, col int) {
 
 // Reveal - 從 row, col 開始翻開周圍不是地雷，直到遇到非零的格子
 func (board *Board) Reveal(row, col int) {
-	// 超出邊界
-	if row < 0 || row >= board.rows ||
-		col < 0 || col >= board.cols {
-		return
-	}
-
-	cell := board.cells[row][col]
-	// 已經被揭開
-	if cell.Revealed {
-		return
-	}
+	visitQueue := []coord{{
+		Row: row,
+		Col: col,
+	}}
+	// 透過 queue 來實做 BFS
+	for len(visitQueue) > 0 {
+		// pop up first
+		cellCoord := visitQueue[0]
+		visitQueue = visitQueue[1:]
+		curRow, curCol := cellCoord.Row, cellCoord.Col
+
+		// 超出邊界
+		if curRow < 0 || curRow >= board.rows ||
+			curCol < 0 || curCol >= board.cols {
+			continue
+		}
 
-	// 標注該格已經被揭開
-	board.cells[row][col].Revealed = true
-	if cell.Flagged {
-		board.RemainingFlags++
-		board.cells[row][col].Flagged = false
-	}
+		cell := board.cells[curRow][curCol]
+		// 已經被揭開
+		if cell.Revealed {
+			continue
+		}
 
-	// 如果是空白格 (AdjacenetMines = 0, 且不是地雷)
-	if !cell.IsMine && cell.AdjacenetMines == 0 {
-		// 鄰近所有方向
-		neighborDirections := [8]coord{
-			{Row: -1, Col: -1}, {Row: -1, Col: 0}, {Row: -1, Col: 1},
-			{Row: 0, Col: -1}, {Row: 0, Col: 1},
-			{Row: 1, Col: -1}, {Row: 1, Col: 0}, {Row: 1, Col: 1},
+		// 標注該格已經被揭開
+		board.cells[curRow][curCol].Revealed = true
+		if cell.Flagged {
+			board.RemainingFlags++
+			board.cells[curRow][curCol].Flagged = false
 		}
-		for _, direction := range neighborDirections {
-			neighborRow, neighborCol := row+direction.Row, col+direction.Col
-			board.Reveal(neighborRow, neighborCol)
+
+		// 如果是空白格 (AdjacenetMines = 0, 且不是地雷)
+		if !cell.IsMine && cell.AdjacenetMines == 0 {
+			// 鄰近所有方向
+			neighborDirections := [8]coord{
+				{Row: -1, Col: -1}, {Row: -1, Col: 0}, {Row: -1, Col: 1},
+				{Row: 0, Col: -1}, {Row: 0, Col: 1},
+				{Row: 1, Col: -1}, {Row: 1, Col: 0}, {Row: 1, Col: 1},
+			}
+			for _, direction := range neighborDirections {
+				neighborRow, neighborCol := curRow+direction.Row, curCol+direction.Col
+				visitQueue = append(visitQueue, coord{
+					Row: neighborRow,
+					Col: neighborCol,
+				})
+			}
 		}
 	}
 }