✨ (2048): add moveLeft function

Author: yuanyu90221

internal/game.go

@@ -53,12 +53,15 @@ func (g *Game) addRandomTile() {
 			}
 		}
 	}
+
 	// 如果所有格子都滿了
 	if len(emptyTiles) == 0 {
 		return
 	}
+
 	// 選出要填入的位置
 	position := emptyTiles[g.randomPositonerFunc(len(emptyTiles))]
+
 	// 90% 機率是 2 , 10%  機率則為 4
 	value := 2
 	if g.randomFunc() < 0.1 {
@@ -67,6 +70,53 @@ func (g *Game) addRandomTile() {
 	g.board[position[0]][position[1]] = value
 }
 
+// slideAndMergeLeft - 向左滑動並且合併
+func (g *Game) slideAndMergeLeft(row []int) []int {
+	// 1 去掉空格
+	filtered := make([]int, 0, len(row))
+	for _, v := range row {
+		if v != 0 {
+			filtered = append(filtered, v)
+		}
+	}
+
+	// 假設沒有空格
+	if len(filtered) == 0 {
+		return row
+	}
+
+	// 2 合併相鄰相同數字
+	for i := 0; i < len(filtered)-1; i++ {
+		if filtered[i] == filtered[i+1] {
+			filtered[i] *= 2
+			filtered[i+1] = 0
+			i++ // 跳過剛合併的數字
+		}
+	}
+
+	// 3 再次去掉空格
+	result := make([]int, 0, len(row))
+	for _, v := range filtered {
+		if v != 0 {
+			result = append(result, v)
+		}
+	}
+
+	// 4 補充剩下的空格為 0
+	for len(result) < len(row) {
+		result = append(result, 0)
+	}
+
+	return result
+}
+
+// moveLeft - 整個 board 同時左移
+func (g *Game) moveLeft() {
+	for r := 0; r < sideSize; r++ {
+		g.board[r] = g.slideAndMergeLeft(g.board[r][:])
+	}
+}
+
 func NewGame() *Game {
 	return &Game{
 		nil,

internal/game_test.go

@@ -243,3 +243,75 @@ func TestGameRandTile(t *testing.T) {
 	}
 
 }
+
+func TestGameMoveLeft(t *testing.T) {
+	type field struct {
+		board [][]int
+	}
+	tests := []struct {
+		name  string
+		input field
+		want  [][]int
+	}{
+		{
+			name: "case1: 單行多次合併",
+			input: field{
+				board: [][]int{
+					{4, 4, 4, 4},
+					{2, 2, 0, 0},
+					{2, 0, 2, 0},
+					{8, 0, 0, 8},
+				},
+			},
+			want: [][]int{
+				{8, 8, 0, 0},
+				{4, 0, 0, 0},
+				{4, 0, 0, 0},
+				{16, 0, 0, 0},
+			},
+		},
+		{
+			name: "case2: 新生成的數字不參與當回合合併",
+			input: field{
+				board: [][]int{
+					{2, 2, 4, 8},
+					{0, 0, 0, 0},
+					{4, 4, 8, 8},
+					{2, 2, 2, 2},
+				},
+			},
+			want: [][]int{
+				{4, 4, 8, 0},
+				{0, 0, 0, 0},
+				{8, 16, 0, 0},
+				{4, 4, 0, 0},
+			},
+		},
+		{
+			name: "case3: 無合併，只有移動",
+			input: field{
+				board: [][]int{
+					{2, 4, 8, 16},
+					{0, 2, 0, 4},
+					{8, 0, 4, 0},
+					{2, 4, 2, 4},
+				},
+			},
+			want: [][]int{
+				{2, 4, 8, 16},
+				{2, 4, 0, 0},
+				{8, 4, 0, 0},
+				{2, 4, 2, 4},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			game := NewGame()
+			game.Init(tt.input.board, nil, nil)
+			// 模擬左移
+			game.moveLeft()
+			assert.Equal(t, tt.want, game.board)
+		})
+	}
+}