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➤微信公众号：山青咏芝（shanqingyongzhi）
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Given a matrix consists of 0 and 1, find the distance of the nearest 0 for each cell.
The distance between two adjacent cells is 1.
Example 1:
Input:
0 0 0 0 1 0 0 0 0
Output:
0 0 0 0 1 0 0 0 0
Example 2:
Input:
0 0 0 0 1 0 1 1 1
Output:
0 0 0 0 1 0 1 2 1
Note:
- The number of elements of the given matrix will not exceed 10,000.
- There are at least one 0 in the given matrix.
- The cells are adjacent in only four directions: up, down, left and right.
给定一个由 0 和 1 组成的矩阵，找出每个元素到最近的 0 的距离。
两个相邻元素间的距离为 1 。
示例 1:
输入:
0 0 0 0 1 0 0 0 0
输出:
0 0 0 0 1 0 0 0 0
示例 2:
输入:
0 0 0 0 1 0 1 1 1
输出:
0 0 0 0 1 0 1 2 1
注意:
- 给定矩阵的元素个数不超过 10000。
- 给定矩阵中至少有一个元素是 0。
- 矩阵中的元素只在四个方向上相邻: 上、下、左、右。
644ms
1 class Solution { 2 func updateMatrix(_ matrix: [[Int]]) -> [[Int]] { 3 let n = matrix.count 4 let m = matrix[0].count 5 let maxDis = n + m 6 var res: [[Int]] = Array(repeating: Array(repeating: 0, count: m), count: n) 7 8 for i in 0 ..< n { 9 for j in 0 ..< m { 10 if matrix[i][j] == 1 { 11 let top = (i > 0) ? res[i - 1][j] : maxDis 12 let l = (j > 0) ? res[i][j - 1] : maxDis 13 res[i][j] = min(maxDis, min(top, l) + 1) 14 } 15 } 16 } 17 18 for i in (0 ..< n).reversed() { 19 for j in (0 ..< m).reversed() { 20 if matrix[i][j] == 1 { 21 let bottom = (i < n - 1) ? res[i + 1][j] : maxDis 22 let r = (j < m - 1) ? res[i][j + 1] : maxDis 23 res[i][j] = min(res[i][j], min(bottom, r) + 1) 24 } 25 } 26 } 27 28 return res 29 } 30 }
Runtime: 652 ms
Memory Usage: 20 MB
1 class Solution { 2 func updateMatrix(_ matrix: [[Int]]) -> [[Int]] { 3 var m:Int = matrix.count 4 var n:Int = matrix[0].count 5 var res:[[Int]] = [[Int]](repeating:[Int](repeating:Int.max - 1,count:n),count:m) 6 for i in 0..<m 7 { 8 for j in 0..<n 9 { 10 if matrix[i][j] == 0 11 { 12 res[i][j] = 0 13 } 14 else 15 { 16 if i > 0 17 { 18 res[i][j] = min(res[i][j], res[i - 1][j] + 1) 19 } 20 if j > 0 21 { 22 res[i][j] = min(res[i][j], res[i][j - 1] + 1) 23 } 24 } 25 } 26 } 27 for i in stride(from:m - 1,through:0,by:-1) 28 { 29 for j in stride(from:n - 1,through:0,by:-1) 30 { 31 if res[i][j] != 0 && res[i][j] != 1 32 { 33 if i < m - 1 34 { 35 res[i][j] = min(res[i][j], res[i + 1][j] + 1) 36 } 37 if j < n - 1 38 { 39 res[i][j] = min(res[i][j], res[i][j + 1] + 1) 40 } 41 } 42 } 43 } 44 return res 45 } 46 }
Runtime: 676 ms
Memory Usage: 20.4 MB
1 class Solution { 2 func updateMatrix(_ matrix: [[Int]]) -> [[Int]] { 3 4 struct Node { 5 var value = 0; 6 var i = 0; 7 var j = 0; 8 } 9 10 var tempArr = matrix; 11 12 var nodeArr = [Node]() 13 var lastNum = 0; 14 for i in 0..<matrix.count { 15 for j in 0..<matrix[i].count { 16 var node: Node = Node.init(); 17 node.i = i; 18 node.j = j; 19 if matrix[i][j] == 0 { 20 node.value = 0; 21 nodeArr.append(node) 22 } else { 23 node.value = -1; 24 lastNum = lastNum + 1; 25 tempArr[i][j] = -1; 26 } 27 } 28 } 29 30 while lastNum > 0 { 31 32 for k in 0..<nodeArr.count { 33 let i = nodeArr[k].i; 34 let j = nodeArr[k].j; 35 //上下左右,并且不是-1 36 if i > 0 && tempArr[i-1][j] == -1 { 37 tempArr[i-1][j] = nodeArr[k].value + 1; 38 let node = Node.init(value: tempArr[i-1][j], i: i-1, j: j); 39 nodeArr.append(node); 40 lastNum = lastNum - 1; 41 } 42 if i + 1 < tempArr.count && tempArr[i+1][j] == -1 { 43 tempArr[i+1][j] = nodeArr[k].value + 1; 44 let node = Node.init(value: tempArr[i+1][j], i: i+1, j: j); 45 nodeArr.append(node); 46 lastNum = lastNum - 1; 47 } 48 if j > 0 && tempArr[i][j-1] == -1 { 49 tempArr[i][j-1] = nodeArr[k].value + 1; 50 let node = Node.init(value: tempArr[i][j-1], i: i, j: j-1); 51 nodeArr.append(node); 52 lastNum = lastNum - 1; 53 } 54 if j + 1 < tempArr[0].count && tempArr[i][j+1] == -1 { 55 tempArr[i][j+1] = nodeArr[k].value + 1; 56 let node = Node.init(value: tempArr[i][j+1], i: i, j: j+1); 57 nodeArr.append(node); 58 lastNum = lastNum - 1; 59 } 60 } 61 } 62 return tempArr; 63 } 64 }
796ms
1 class Solution { 2 func updateMatrix(_ matrix: [[Int]]) -> [[Int]] { 3 4 var matrix = matrix 5 6 for row in 0..<matrix.count { 7 for column in 0..<matrix[row].count where matrix[row][column] != 0 { 8 var minDistance = Int.max - 1 9 10 //up 11 if row > 0 { 12 minDistance = min(minDistance, matrix[row-1][column]) 13 } 14 15 //left 16 if column > 0 { 17 minDistance = min(minDistance, matrix[row][column-1]) 18 } 19 20 matrix[row][column] = minDistance + 1 21 } 22 } 23 24 25 for row in (0..<matrix.count).reversed() { 26 for column in (0..<matrix[row].count).reversed() where matrix[row][column] != 0 { 27 var minDistance = matrix[row][column] 28 29 //down 30 if row < matrix.count - 1 { 31 minDistance = min(minDistance, (matrix[row+1][column] + 1)) 32 } 33 34 //right 35 if column < matrix[row].count - 1 { 36 minDistance = min(minDistance, (matrix[row][column+1] + 1)) 37 } 38 39 matrix[row][column] = minDistance 40 } 41 } 42 43 return matrix 44 } 45 }
976ms
1 class Solution { 2 func updateMatrix(_ matrix: [[Int]]) -> [[Int]] { 3 var res = matrix 4 if matrix.count == 0 || matrix[0].count == 0 { 5 return res 6 } 7 let dx = [0,0,1,-1] 8 let dy = [1,-1,0,0] 9 let n = matrix.count 10 let m = matrix[0].count 11 var queue = [[Int]]() 12 for i in 0 ..< n { 13 for j in 0 ..< m { 14 if res[i][j] != 0 { 15 res[i][j] = Int.max 16 }else { 17 queue.append([i, j]) 18 } 19 } 20 } 21 22 while !queue.isEmpty { 23 let cur = queue.removeFirst() 24 for i in 0 ... 3 { 25 let nx = dx[i] + cur[0] 26 let ny = dy[i] + cur[1] 27 if nx < res.count && ny < res[0].count && nx >= 0 && ny >= 0 { 28 if res[nx][ny] > res[cur[0]][cur[1]] + 1 { 29 res[nx][ny] = res[cur[0]][cur[1]] + 1 30 queue.append([nx, ny]) 31 } 32 } 33 } 34 } 35 36 return res 37 } 38 }
1004ms
1 class Solution { 2 func updateMatrix(_ matrix: [[Int]]) -> [[Int]] { 3 var res = matrix 4 if matrix.count == 0 || matrix[0].count == 0 { 5 return res 6 } 7 let n = matrix.count 8 let m = matrix[0].count 9 var visited = [[Bool]](repeating: [Bool](repeating: false, count: m), count: n) 10 11 for i in 0 ..< n { 12 for j in 0 ..< m { 13 if res[i][j] == 0 { 14 fill(&res, &visited, i, j , 0) 15 } 16 } 17 } 18 return res 19 } 20 21 22 func fill(_ res: inout [[Int]], _ visited: inout [[Bool]], _ x: Int, _ y: Int, _ count :Int) { 23 visited[x][y] = true 24 let dx = [0,0,-1,1] 25 let dy = [1,-1,0,0] 26 res[x][y] = count 27 for i in 0 ... 3{ 28 let nx = dx[i] + x 29 let ny = dy[i] + y 30 if nx >= 0 && ny >= 0 && nx < res.count && ny < res[0].count && res[nx][ny] != 0{ 31 if count > 1 && hasNeiborZero(res, [nx, ny]){ 32 continue 33 } 34 if !visited[nx][ny] || res[nx][ny] > count + 1 { 35 fill(&res, &visited, nx, ny, count + 1) 36 } 37 } 38 } 39 40 } 41 func hasNeiborZero(_ maze:[[Int]], _ index:[Int]) -> Bool{ 42 let x = index[0] 43 let y = index[1] 44 if x > 0 && maze[x - 1][y] == 0 { 45 return true 46 } 47 if y > 0 && maze[x][y - 1] == 0 { 48 return true 49 } 50 if y < maze[0].count - 1 && maze[x][y + 1] == 0 { 51 return true 52 } 53 if x < maze.count - 1 && maze[x + 1][y] == 0 { 54 return true 55 } 56 return false 57 58 } 59 }
1068ms
1 class Solution { 2 func updateMatrix(_ matrix: [[Int]]) -> [[Int]] { 3 let dirs: [(Int, Int)] = [(0, -1), (-1, 0), (1, 0), (0, 1)] 4 let n = matrix.count 5 let m = matrix[0].count 6 var queue: [(Int, Int)] = [] 7 var res: [[Int]] = Array(repeating: Array(repeating: 0, count: m), count: n) 8 9 for i in 0 ..< n { 10 for j in 0 ..< m { 11 if matrix[i][j] == 0 { 12 queue.append((i, j)) 13 } else { 14 res[i][j] = Int.max 15 } 16 } 17 } 18 19 while !queue.isEmpty { 20 let curr = queue.removeFirst() 21 for d in dirs { 22 let x = curr.0 + d.0 23 let y = curr.1 + d.1 24 if x < 0 || x >= n || y < 0 || y >= m || res[x][y] <= res[curr.0][curr.1] + 1 { 25 continue 26 } 27 res[x][y] = res[curr.0][curr.1] + 1 28 queue.append((x, y)) 29 } 30 } 31 return res 32 } 33 }
1124ms
1 class Solution { 2 func updateMatrix(_ matrix: [[Int]]) -> [[Int]] { 3 var matrix = matrix 4 if matrix == nil || matrix.count == 0 || matrix[0] == nil || matrix[0].count == 0 { 5 return [[Int]]() 6 } 7 8 let m = matrix.count 9 let n = matrix[0].count 10 11 var temp = Array(repeating:0,count:n) 12 var result = Array(repeating:temp,count:m) 13 var queue = [Point]() 14 for i in 0 ..< m{ 15 for j in 0 ..< n{ 16 17 if matrix[i][j] == 0{ 18 result[i][j] = 0 19 queue.append(Point(i,j,0)) 20 }else{ 21 result[i][j] = Int.max 22 } 23 } 24 } 25 26 27 while !queue.isEmpty{ 28 29 30 let point = queue.removeFirst() 31 32 let deltaX = [0,0,1,-1] 33 let deltaY = [1,-1,0,0] 34 35 36 for i in 0 ..< 4 { 37 38 if point.x + deltaX[i] >= 0 && point.x + deltaX[i] < m && point.y + deltaY[i] >= 0 && 39 point.y + deltaY[i] < n && result[point.x+deltaX[i]][point.y+deltaY[i]] == Int.max{ 40 result[point.x+deltaX[i]][point.y+deltaY[i]] = point.level + 1 41 42 queue.append(Point(point.x+deltaX[i],point.y+deltaY[i],point.level+1)) 43 } 44 } 45 } 46 47 return result 48 } 49 } 50 51 class Point{ 52 var x = 0 53 var y = 0 54 var level = 0 55 init(_ x: Int, _ y:Int, _ level:Int){ 56 self.x = x 57 self.y = y 58 self.level = level 59 } 60 }