[Swift]LeetCode959. 由斜杠划分区域 | Regions Cut By Slashes
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➤微信公众号：山青咏芝（shanqingyongzhi）
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In a N x N grid composed of 1 x 1 squares, each 1 x 1 square consists of a /, \, or blank space. These characters divide the square into contiguous regions.
(Note that backslash characters are escaped, so a \ is represented as "\\".)
Return the number of regions.
Example 1:
Input:
[
" /",
"/ "
]
Output: 2
Explanation: The 2x2 grid is as follows:
Example 2:
Input:
[
" /",
" "
]
Output: 1
Explanation: The 2x2 grid is as follows:
Example 3:
Input:
[
"\\/",
"/\\"
]
Output: 4
Explanation: (Recall that because \ characters are escaped, "\\/" refers to \/, and "/\\" refers to /\.)
The 2x2 grid is as follows:
Example 4:
Input:
[
"/\\",
"\\/"
]
Output: 5
Explanation: (Recall that because \ characters are escaped, "/\\" refers to /\, and "\\/" refers to \/.)
The 2x2 grid is as follows:
Example 5:
Input:
[
"//",
"/ "
]
Output: 3
Explanation: The 2x2 grid is as follows:
Note:
1 <= grid.length == grid[0].length <= 30grid[i][j]is either'/','\', or' '.
在由 1 x 1 方格组成的 N x N 网格 grid 中，每个 1 x 1 方块由 /、\ 或空格构成。这些字符会将方块划分为一些共边的区域。
（请注意，反斜杠字符是转义的，因此 \ 用 "\\" 表示。）。
返回区域的数目。
示例 1：
输入： [ " /", "/ " ] 输出：2 解释：2x2 网格如下：
示例 2：
输入： [ " /", " " ] 输出：1 解释：2x2 网格如下：
示例 3：
输入： [ "\\/", "/\\" ] 输出：4 解释：（回想一下，因为 \ 字符是转义的，所以 "\\/" 表示 \/，而 "/\\" 表示 /\。） 2x2 网格如下：
示例 4：
输入： [ "/\\", "\\/" ] 输出：5 解释：（回想一下，因为 \ 字符是转义的，所以 "/\\" 表示 /\，而 "\\/" 表示 \/。） 2x2 网格如下：
示例 5：
输入： [ "//", "/ " ] 输出：3 解释：2x2 网格如下：
提示：
1 <= grid.length == grid[0].length <= 30grid[i][j]是'/'、'\'、或' '。
104ms
1 class Solution { 2 let TOP = 0, LEFT = 1, RIGHT = 2, BOTTOM = 3 3 4 func regionsBySlashes(_ grid: [String]) -> Int { 5 var len:Int = grid.count 6 //定义三维数组，元素初始化为0，由内往外 7 var g = [[[Int]]](repeating: [[Int]](repeating: [Int](repeating: 0, count: 4), count: len), count: len) 8 var n:Int = 0 9 for i in 0..<len 10 { 11 for j in 0..<len 12 { 13 for k in 0..<4 14 { 15 if g[i][j][k] == 0 16 { 17 n += 1 18 mark(grid, &g, i, j, k, n) 19 } 20 } 21 } 22 } 23 return n 24 } 25 26 func mark(_ grid:[String],_ g: inout [[[Int]]],_ i:Int,_ j:Int,_ k:Int,_ n: Int) 27 { 28 var len:Int = g.count 29 if i < 0 || i >= len || j < 0 || j >= len || g[i][j][k] != 0 {return} 30 g[i][j][k] = n 31 var c:Character = grid[i][j] 32 if c == "/" 33 { 34 if k == LEFT || k == TOP 35 { 36 mark(grid, &g, i, j, LEFT, n) 37 mark(grid, &g, i, j, TOP, n) 38 } 39 else 40 { 41 mark(grid, &g, i, j, BOTTOM, n) 42 mark(grid, &g, i, j, RIGHT, n) 43 } 44 } 45 else if c == "\\" 46 { 47 if k == LEFT || k == BOTTOM 48 { 49 mark(grid, &g, i, j, LEFT, n) 50 mark(grid, &g, i, j, BOTTOM, n) 51 } 52 else 53 { 54 mark(grid, &g, i, j, TOP, n) 55 mark(grid, &g, i, j, RIGHT, n) 56 } 57 } 58 else 59 { 60 mark(grid, &g, i, j, TOP, n) 61 mark(grid, &g, i, j, LEFT, n) 62 mark(grid, &g, i, j, RIGHT, n) 63 mark(grid, &g, i, j, BOTTOM, n) 64 } 65 66 if k == LEFT 67 { 68 mark(grid, &g, i, j - 1, RIGHT, n) 69 } 70 else if k == RIGHT 71 { 72 mark(grid, &g, i, j + 1, LEFT, n) 73 } 74 else if k == BOTTOM 75 { 76 mark(grid, &g, i + 1, j, TOP, n) 77 } 78 else if k == TOP 79 { 80 mark(grid, &g, i - 1, j, BOTTOM, n) 81 } 82 } 83 } 84 85 extension String { 86 //subscript函数可以检索数组中的值 87 //直接按照索引方式截取指定索引的字符 88 subscript (_ i: Int) -> Character { 89 //读取字符 90 get {return self[index(startIndex, offsetBy: i)]} 91 } 92 }
180ms
1 class Solution { 2 func regionsBySlashes(_ grid: [String]) -> Int { 3 let N = grid.count 4 let dsu = DSU(4 * N * N) 5 for r in 0..<N { 6 for c in 0..<N { 7 let root = 4 * (r * N + c) 8 let val = Array(grid[r])[c] 9 if val != "\\" { 10 dsu.union(root, root + 1) 11 dsu.union(root + 2, root + 3) 12 } 13 if val != "/" { 14 dsu.union(root, root + 2) 15 dsu.union(root + 1, root + 3) 16 } 17 if r + 1 < N { 18 dsu.union(root + 3, root + 4 * N) 19 } 20 if r - 1 >= 0 { 21 dsu.union(root, root - 4 * N + 3) 22 } 23 if c + 1 < N { 24 dsu.union(root + 2, root + 4 + 1) 25 } 26 if c - 1 >= 0 { 27 dsu.union(root + 1, root - 4 + 2) 28 } 29 } 30 } 31 var ans = 0 32 for x in 0..<4 * N * N where dsu.find(x) == x { ans += 1 } 33 return ans 34 } 35 } 36 37 class DSU { 38 var parent: [Int] 39 init(_ N: Int) { 40 parent = Array(repeating: 0, count: N) 41 for i in 0..<N { parent[i] = i } 42 } 43 func find(_ x: Int) -> Int { 44 if parent[x] != x { parent[x] = find(parent[x]) } 45 return parent[x] 46 } 47 func union(_ x: Int, _ y: Int) { 48 parent[find(x)] = find(y) 49 } 50 }
200ms
1 class Solution { 2 let convertDict: [Character: [[Int]]] = [ 3 "/": [[0,0,1], [0,1,0], [1,0,0]], 4 "\\": [[1,0,0], [0,1,0], [0,0,1]] 5 ] 6 7 func regionsBySlashes(_ grid: [String]) -> Int { 8 // convert 9 var map = [[Int]]() 10 for row in grid { 11 var line0 = [Int](), line1 = [Int](), line2 = [Int]() 12 for (idx, char) in row.enumerated() { 13 let converted = convertDict[char] ?? [[0,0,0],[0,0,0],[0,0,0]] 14 line0 += converted[0] 15 line1 += converted[1] 16 line2 += converted[2] 17 } 18 map += [line0, line1, line2] 19 } 20 21 // perform 22 var result = 0 23 for i in 0..<map.count { 24 for j in 0..<map[i].count { 25 if map[i][j] == 0 { 26 result += 1 27 dfs(i, j, &map) 28 } 29 } 30 } 31 return result 32 } 33 34 func dfs(_ i: Int, _ j: Int, _ map: inout [[Int]]) { 35 guard i >= 0 && i < map.count else { return } 36 let row = map[i] 37 guard j >= 0 && j < row.count else { return } 38 guard map[i][j] == 0 else { return } 39 map[i][j] = -1 40 dfs(i-1, j, &map) 41 dfs(i+1, j, &map) 42 dfs(i, j-1, &map) 43 dfs(i, j+1, &map) 44 } 45 }
