[Swift]LeetCode130. 被围绕的区域 | Surrounded Regions

概述Given a 2D board containing ‘X‘ and ‘O‘ (the letter O), capture all regions surrounded by ‘X‘. A region is captured by flipping all ‘O‘s into ‘X‘s in that surrounded region. Example: X X X XX O O X

Given a 2D board containing ‘X‘ and ‘O‘ (the letter O),capture all regions surrounded by ‘X‘.

A region is captured by flipPing all ‘O‘s into ‘X‘s in that surrounded region.

Example:

X X X XX O O XX X O XX O X X

After running your function,the board should be:

X X X XX X X XX X X XX O X X

Explanation:

Surrounded regions shouldn’t be on the border,which means that any ‘O‘ on the border of the board are not flipped to ‘X‘. Any ‘O‘ that is not on the border and it is not connected to an ‘O‘ on the border will be flipped to ‘X‘. Two cells are connected if they are adjacent cells connected horizontally or vertically.

 给定一个二维的矩阵，包含 ‘X‘ 和 ‘O‘（字母 O）。

找到所有被 ‘X‘ 围绕的区域，并将这些区域里所有的 ‘O‘ 用 ‘X‘ 填充。

示例:

X X X XX O O XX X O XX O X X

运行你的函数后，矩阵变为：

X X X XX X X XX X X XX O X X

解释:

被围绕的区间不会存在于边界上，换句话说，任何边界上的 ‘O‘ 都不会被填充为 ‘X‘。 任何不在边界上，或不与边界上的 ‘O‘ 相连的 ‘O‘ 最终都会被填充为 ‘X‘。如果两个元素在水平或垂直方向相邻，则称它们是“相连”的。

52ms

 1 class Solution { 2     func solve(_ board: inout [[Character]]) { 3         let h = board.count 4         guard h > 2 else { return } 5          6         let w = board[0].count 7         guard w > 2 else { return } 8          9         for i in 0..<h {10             mark(&board,i,0)11             mark(&board,w - 1)12         }13         14         for j in 0..<w {15             mark(&board,0,j)16             mark(&board,h - 1,j)17         }18         19         for i in 0..<h {20             for j in 0..<w {21                 if board[i][j] == "O" {22                    board[i][j] = "X"23                 } else if board[i][j] == "T" {24                    board[i][j] = "O"25                 }26             }27         }28     }29     30     func mark(_ board: inout [[Character]],_ i: Int,_ j: Int) {31         guard i >= 0 && i < board.count else { return }32         guard j >= 0 && j < board[i].count else { return }33         guard board[i][j] == "O" else { return }34         35         board[i][j] = "T"36         37         mark(&board,i - 1,j)38         mark(&board,i + 1,j)39         mark(&board,j - 1)40         mark(&board,j + 1)41     }42 }

56ms

 1 class Solution { 2     func solve(_ board: inout [[Character]]) { 3         for i in 0..<board.count { 4             for j in 0..<board[i].count { 5                 if (i == 0 || i == board.count - 1 || j == 0 || j == board[i].count - 1) && board[i][j] == "O" { 6                     dfs(&board,j) 7                 } 8  9             }10         }11         for i in 0..<board.count {12             for j in 0..<board[i].count {13                 if board[i][j] == "O" {14                     board[i][j] = "X"15                 }16                 if board[i][j] == "Y" {17                     board[i][j] = "O"18                 }19             }20         }21     }22     private func dfs(_ board: inout [[Character]],_ j: Int) {23         if board[i][j] == "O" {24 25             board[i][j] = "Y"26             if i > 0 && board[i - 1][j] == "O" {27                 dfs(&board,j)28             }29 30             if j < board[i].count - 1 && board[i][j + 1] == "O" {31                 dfs(&board,j + 1)32             }33 34             if i < board.count - 1 && board[i + 1][j] == "O" {35                 dfs(&board,j)36             }37 38             if j > 0 && board[i][j - 1] == "O" {39                 dfs(&board,j - 1)40             }41         }42     }43 }

60ms

 1 class Solution { 2     func solve(_ board: inout [[Character]]) { 3         guard board.count > 0 && board[0].count > 0 else { 4             return 5         } 6          7         let countRow = board.count - 1 8         let countCol = board[0].count - 1 9         10         var visited = [[Bool]](repeating:[Bool](repeating: false,count: countCol+1),count: countRow+1)11         var boarder0Indexs = [(Int,Int)]()12         13         let direction  = [(-1,0),(1,(0,-1),1)] // top bot left right14         15         for row in 0...countRow {16             for col in 0...countCol {17                 if row == 0 || col == 0 || row == countRow || col == countCol {18                     if board[row][col] == "O" {19                         board[row][col] = "B"20                         boarder0Indexs.append((row,col))21                     }                    22                 }23             }24         }25         26         for item in boarder0Indexs {27             let row = item.028             let col = item.129              30             var tempQueue = [(Int,Int)]()31             tempQueue.append(item)32             33             //bfs34             while (!tempQueue.isEmpty) {35                 let count = tempQueue.count36                 for _ in 0..<count {37                     let curItem = tempQueue.removeFirst()38                     let curRow = curItem.039                     let curCol = curItem.140                     //check adjacent cells 41                     for dirt in direction {42                         let nextLevelRow = curRow + dirt.043                         let nextLevelCol = curCol + dirt.1  44                         //make sure not out of bounce45                         if nextLevelRow <= countRow && nextLevelRow >= 0 && nextLevelCol <= countCol && nextLevelCol >= 0 {46                             if !visited[nextLevelRow][nextLevelCol] {47                                 if board[nextLevelRow][nextLevelCol] == "O" {48                                     board[nextLevelRow][nextLevelCol] = "B"49                                     tempQueue.append((nextLevelRow,nextLevelCol))50                                 } 51                                 visited[nextLevelRow][nextLevelCol] = true52                             }   53                         }                       54                     }55                 }56             }       57         }58         for i in 0...countRow {59             for j in 0...countCol {60                 if  board[i][j] == "B" {61                     board[i][j] = "O"62                 } else if board[i][j] == "O" {63                     board[i][j] = "X"64                 }65             }66         }67     }68 }

80ms

 1 class Solution { 2     func solve(_ board: inout [[Character]]) { 3         for i in 0..<board.count{ 4             for j in 0..<board[0].count{ 5                 if (i==0 || i == board.count - 1 || j == 0 || j == board[0].count - 1) && board[i][j] == "O" { 6                     board[i][j] = "M" 7                     connected(i,j,&board) 8                 } 9             }10         }11         for i in 0..<board.count{12             for j in 0..<board[0].count{13                 if board[i][j] == "O" {14                     board[i][j] = "X"15                 }16                 else if board[i][j] == "M" {17                     board[i][j] = "O"18                 }    19             }20         }21     }22     private func connected(_ i : Int,_ j : Int,_ board: inout [[Character]]){23         if i-1 > 0 && board[i-1][j] == "O" {24             board[i-1][j] = "M"25             connected(i-1,&board)26         }27         if i+1 < board.count-1 && board[i+1][j] == "O" {28             board[i+1][j] = "M"29             connected(i+1,&board)30         }31         if j-1 > 0 && board[i][j-1] == "O" {32             board[i][j-1] = "M"33             connected(i,j-1,&board)34         }35         if j+1 < board[i].count-1 && board[i][j+1] == "O" {36             board[i][j+1] = "M"37             connected(i,j+1,&board)38         }39     }40 }

176ms

  1 let X = Character("X")  2 let O = Character("O")  3   4 class Solution {  5   6     func solve(_ board: inout [[Character]]) {  7         guard let columnCount = board.first?.count else {  8             return  9         } 10         let rowCount = board.count 11         let uf = UnionFind(rowCount: rowCount,columnCount: columnCount) 12  13         board.enumerated().forEach { i,row in 14             row.enumerated().forEach { j,item in 15                 guard item == O else { 16                     return 17                 } 18  19                 if i == 0 || i == rowCount - 1 || j == 0 || j == columnCount - 1 { 20                     uf.open(i,j) 21                 } 22  23                 // top 24                 if i > 0 && board[i - 1][j] == O { 25                     uf.union(i,j) 26                 } 27  28                 // bottom 29                 if i < rowCount - 1 && board[i + 1][j] == O { 30                     uf.union(i,j) 31                 } 32  33                 // left 34                 if j > 0 && board[i][j - 1] == O { 35                     uf.union(i,j - 1) 36                 } 37  38                 // right 39                 if j < columnCount - 1 && board[i][j + 1] == O { 40                     uf.union(i,j + 1) 41                 } 42             } 43         } 44  45         for i in 0..<rowCount { 46             for j in 0..<columnCount where board[i][j] == O { 47                 if !uf.isOpen(i,j) { 48                     board[i][j] = X 49                 } 50             } 51         } 52     } 53  54 } 55  56 class UnionFind { 57  58     var parent: [Int] 59     var sizes: [Int] 60  61     private let rowCount: Int 62     private let columnCount: Int 63  64     private var opened: [Bool] 65  66     init(rowCount: Int,columnCount: Int) { 67         self.rowCount = rowCount 68         self.columnCount = columnCount 69  70         let count = rowCount * columnCount 71  72         sizes = Array(repeating: 1,count: count) 73         parent = Array(repeating: 0,count: count) 74         opened = Array(repeating: false,count: count) 75  76         for i in 0..<count { 77             parent[i] = i 78         } 79     } 80  81     func isOpen(_ i: Int,_ j: Int) -> Bool { 82         return opened[find(i,j)] 83     } 84  85     func open(_ i: Int,_ j: Int) { 86         let index = calculateIndex(i,j) 87         opened[index] = true 88     } 89  90     func union(_ li: Int,_ lj: Int,_ ri: Int,_ rj: Int) { 91         let rootleft = find(li,lj) 92         let rootRight = find(ri,rj) 93  94         if li == 0 || li == rowCount - 1 || lj == 0 || lj == columnCount - 1 { 95             open(li,lj) 96         } 97         if ri == 0 || ri == rowCount - 1 || rj == 0 || rj == columnCount - 1 { 98             open(ri,rj) 99         }100 101         if rootleft == rootRight {102             return103         }104 105         if opened[rootleft] {106             parent[rootRight] = parent[rootleft]107             sizes[rootleft] += sizes[rootRight]108             return109         }110         if opened[rootRight] {111             parent[rootleft] = parent[rootRight]112             sizes[rootRight] += sizes[rootleft]113             return114         }115 116         if sizes[rootleft] > sizes[rootRight] {117             parent[rootRight] = parent[rootleft]118             sizes[rootleft] += sizes[rootRight]119         } else {120             parent[rootleft] = parent[rootRight]121             sizes[rootRight] += sizes[rootleft]122         }123     }124 125     func find(_ i: Int,_ j: Int) -> Int {126         var index = calculateIndex(i,j)127         while index != parent[index] {128             parent[index] = parent[parent[index]]129             index = parent[index]130         }131         return index132     }133 134     private func calculateIndex(_ i: Int,_ j: Int) -> Int {135         return i * columnCount + j136     }137 }

316ms

 1 class Solution { 2     func solve(_ board: inout [[Character]]) { 3         for i in 0..<board.count 4         { 5             for j in 0..<board[i].count 6             { 7                 if (i == 0 || i == board.count - 1 || j == 0 || j == board[i].count - 1) && board[i][j] == "O" 8                 { 9                     solveDFS(&board,j)10                 }11             }12         }13         for i in 0..<board.count14         {15             for j in 0..<board[i].count16             {17                 if board[i][j] == "O" {board[i][j] = "X"}18                 if board[i][j] == "$" {board[i][j] = "O"}19             }20         }21     }22     23     func solveDFS(_ board: inout [[Character]],_ i:Int,_ j:Int)24     {25         if board[i][j] == "O"26         {27             board[i][j] = "$"28             if i > 0 && board[i - 1][j] == "O"29             {30                 solveDFS(&board,j)31             }32             if j < board[i].count - 1 && board[i][j + 1] == "O"33             {34                 solveDFS(&board,j + 1)35             }36             if i < board.count - 1 && board[i + 1][j] == "O"37             {38                 solveDFS(&board,j)39             }40             if j > 1 && board[i][j - 1] == "O"41             {42                 solveDFS(&board,j - 1)43             }44         }45     }46 }

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