[Swift]LeetCode885. 螺旋矩阵 III | Spiral Matrix III

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On a 2 dimensional grid with R rows and C columns, we start at (r0, c0) facing east.

Here, the north-west corner of the grid is at the first row and column, and the south-east corner of the grid is at the last row and column.

Now, we walk in a clockwise spiral shape to visit every position in this grid. 

Whenever we would move outside the boundary of the grid, we continue our walk outside the grid (but may return to the grid boundary later.) 

Eventually, we reach all R * C spaces of the grid.

Return a list of coordinates representing the positions of the grid in the order they were visited.

Example 1:

Input: R = 1, C = 4, r0 = 0, c0 = 0
Output: [[0,0],[0,1],[0,2],[0,3]]

Example 2:

Input: R = 5, C = 6, r0 = 1, c0 = 4
Output: [[1,4],[1,5],[2,5],[2,4],[2,3],[1,3],[0,3],[0,4],[0,5],[3,5],[3,4],[3,3],[3,2],[2,2],[1,2],[0,2],[4,5],[4,4],[4,3],[4,2],[4,1],[3,1],[2,1],[1,1],[0,1],[4,0],[3,0],[2,0],[1,0],[0,0]]

Note:

1. 1 <= R <= 100
2. 1 <= C <= 100
3. 0 <= r0 < R
4. 0 <= c0 < C

---

在 R 行 C 列的矩阵上，我们从 (r0, c0) 面朝东面开始

这里，网格的西北角位于第一行第一列，网格的东南角位于最后一行最后一列。

现在，我们以顺时针按螺旋状行走，访问此网格中的每个位置。

每当我们移动到网格的边界之外时，我们会继续在网格之外行走（但稍后可能会返回到网格边界）。

最终，我们到过网格的所有 R * C 个空间。

按照访问顺序返回表示网格位置的坐标列表。

示例 1：

输入：R = 1, C = 4, r0 = 0, c0 = 0
输出：[[0,0],[0,1],[0,2],[0,3]]

示例 2：

输入：R = 5, C = 6, r0 = 1, c0 = 4
输出：[[1,4],[1,5],[2,5],[2,4],[2,3],[1,3],[0,3],[0,4],[0,5],[3,5],[3,4],[3,3],[3,2],[2,2],[1,2],[0,2],[4,5],[4,4],[4,3],[4,2],[4,1],[3,1],[2,1],[1,1],[0,1],[4,0],[3,0],[2,0],[1,0],[0,0]]

 

提示：

1. 1 <= R <= 100
2. 1 <= C <= 100
3. 0 <= r0 < R
4. 0 <= c0 < C

---

Runtime: 128 ms

Memory Usage: 19.7 MB

class Solution {
    func spiralMatrixIII(_ R: Int, _ C: Int, _ r0: Int, _ c0: Int) -> [[Int]] {
        var r = r0
        var c = c0
        var res:[[Int]] = [[Int]](repeating:[Int](repeating:0,count:2),count:R * C)
        res[0] = [r, c]
        var x:Int = 0
        var y:Int = 1
        var n:Int = 0
        var i:Int = 0
        var tmp:Int = 0
        var j:Int = 1
        while (j < R * C)
        {
            r += x
            c += y
            i += 1
            if 0 <= r && r < R && 0 <= c && c < C
            {
                res[j] = [r, c]
                j += 1
            }
            if i == (n / 2 + 1)
            {
                i = 0
                n += 1 
                tmp = x
                x = y
                y = -tmp
            }
        }
        return res
    }
}

---

128ms

class Solution {
    func spiralMatrixIII(_ R: Int, _ C: Int, _ r0: Int, _ c0: Int) -> [[Int]] {
        var result = [[Int]]()
        var i = r0
        var j = c0
        var currentLevel = 1
        self.appendResultIfInMatrix(&result,i,j,R,C) //adding first element
        while true {
            for _ in 1 ... currentLevel {
                j += 1
                self.appendResultIfInMatrix(&result,i,j,R,C)
            }
            if result.count == R*C {
                break
            }
            for _ in 1 ... currentLevel {
                i += 1
                self.appendResultIfInMatrix(&result,i,j,R,C)
            }
            if result.count == R*C {
                break
            }
            currentLevel += 1
            for _ in 1 ... currentLevel {
                j -= 1
                self.appendResultIfInMatrix(&result,i,j,R,C)
            }
            if result.count == R*C {
                break
            }
            for _ in 1 ... currentLevel {
                i -= 1
                self.appendResultIfInMatrix(&result,i,j,R,C)
            }
            if result.count == R*C {
                break
            }
            currentLevel += 1
        }
        return result
    }
    
    func appendResultIfInMatrix(_ result: inout [[Int]], _ i:Int, _ j:Int, _ R:Int, _ C: Int) {
        if self.inMatrix(i,j,R,C) {
            result.append([i,j])
        }
    }
    
    func inMatrix(_ i:Int, _ j:Int, _ R:Int, _ C: Int) -> Bool {
        if i >= 0 && i < R && j >= 0 && j < C {
            return true
        } else {
            return false
        }
    }
}

---

140ms

class Solution {
    //first: true for row, false for col; second: true forward, false backward
    private let op = [(true,1),(false,1),(true,-1),(false,-1)] 
    private var ans = [[Int]]()
    private var current = [Int]()
    var visited = 1
    
    func spiralMatrixIII(_ R: Int, _ C: Int, _ r0: Int, _ c0: Int) -> [[Int]] {
        var step = 1; var turningCount = 0
        self.visited = 1
        self.current = [r0,c0]
        self.ans = [current]
        let total = R*C
        
        while (visited != total) {
            let turningSignal = op[turningCount%4]
            move(turningSignal.0, turningSignal.1, step, R, C)
            turningCount += 1
            if (turningCount&1 == 0) {
                step += 1
            }
        }
        
        return ans
    }
    
    private func move(_ direction: Bool, _ forward: Int, _ step: Int, _ R: Int, _ C: Int) {
        for _ in 0..<step {
            if direction {
                current[1] += forward
            } else {
                current[0] += forward
            }
            let row = current[0]; let col = current[1]
            if (row < R && row >= 0 && col < C && col >= 0) {
                ans.append(current)
                visited += 1
            }
        }
    }
}

---

152ms

class Solution {
    func spiralMatrixIII(_ R: Int, _ C: Int, _ r0: Int, _ c0: Int) -> [[Int]] {
        var count = 1
        var right = 0
        var down = 0
        var left = 0
        var up = 0
        var currentRow = r0
        var currentCol = c0
        var pointsCount = 0
        var visitedPoints:[[Int]] = []

        while pointsCount < R*C {
            if currentRow >= 0 && currentRow < R && currentCol >= 0 && currentCol < C {
                pointsCount = pointsCount + 1
                visitedPoints.append([currentRow, currentCol])
            }

            if right < count {
                currentCol  = currentCol + 1
                right = right + 1
            }else if down < right {
                currentRow = currentRow + 1
                down = down + 1
            }else if left < right + 1{
                currentCol  = currentCol - 1
                left = left + 1
            }else if up < right + 1 {
                currentRow = currentRow - 1
                up = up + 1
            }

            if up == right + 1 {
                count = count + 2
                right = 0
                down = 0
                left = 0
                up = 0
            }
        }
        return visitedPoints
    }
}

---

204ms

class Solution {
    func spiralMatrixIII(_ R: Int, _ C: Int, _ r0: Int, _ c0: Int) -> [[Int]] {        
        var r = r0,c = c0,n = 1,direction = 1,count = 1
        var arr : Array<Array<Int>> = [[]]
        arr.removeAll()
        arr.append([r,c])
        while arr.count < R * C {
            
            switch direction%4 {//上右下左
            case 0: r-=1
            case 1: c+=1
            case 2: r+=1
            case 3: c-=1
            default: break
            }
            if (r >= 0 && r < R && c >= 0 && c < C) {
                arr.append([r,c])
            }
            
            if count < n {
                count += 1
            } else {
            if direction % 4 == 0 || direction % 4 == 2 {
                n+=1
            }
            count = 1
       direction += 1
            }
        }
        return arr        
    }
}

---

212ms

class Solution {
    func spiralMatrixIII(_ R: Int, _ C: Int, _ r0: Int, _ c0: Int) -> [[Int]] {
    var arr: [[Int]] = [[r0, c0]]
    
    // 0 →  1 ↓  2 ←  3 ↑
    var dir = 0
    var dis = 1, cis = 1
    var r = r0, c = c0
    let max = R * C
    
    while true {
        if arr.count == max { break }
        let n = next(dir, r, c)
        r = n.0
        c = n.1
        
        cis -= 1
        if cis == 0 {
            dir += 1
            if dir % 2 == 0 {
                dis += 1
            }
            cis = dis
        }
        
        if outRect(R, C, r, c: c) { continue }
        arr.append([r, c])
    }
    
    return arr
}

func outRect(_ R: Int, _ C: Int, _ r: Int, c: Int) -> Bool {
    return (r < 0 || r >= R) || (c < 0 || c >= C)
}

func next(_ dir: Int, _ r: Int, _ c: Int) -> (Int, Int) {
    let d = dir % 4
    switch d {
    case 0: return (r, c+1)
    case 1: return (r+1, c)
    case 2: return (r, c-1)
    case 3: return (r-1, c)
    default:return (r, c)
    }
  }
}