885. Spiral Matrix III

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 are at the first row and column, and the South-east corner of the grid are at the LA St row and column.

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

Whenever we would move outside the boundary of the grid, we continue our walk outside the grid (and 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

Class Solution:def spiralmatrixiii (self, R, C, R0, C0): "" ": Type R:int:type C:int:typ        e r0:int:type C0:int:rtype:list[list[int]] "" "count = 1 L = 1 res = []                 Direction = 1 Res.append ([r0,c0]) while count<r*c:if direction==1:c0 + = L                    # print (' Direction:1,pos: ', r0,c0) for I in Range (c0-l+1,c0+1): #不考虑起点, consider the end point                If 0<=r0<r and 0<=i<c:res.append ([r0,i]) Count + = 1            # print (count) # Print (res) Direction = 2 Continue If direction==2:r0 + = l # print (' Direction:2,pos: ', r0,c0) for I in range (r0-                        L+1,R0+1): If 0<=i<r and 0<=c0<c:res.append ([i,c0])      Count + = 1          # print (count) # Print (res) Direction = 3 L + = 1                Continue if direction==3:c0-= l # print (' Direction:3,pos: ', r0,c0) For I in Range (c0+l-1,c0-1,-1): If 0<=r0<r and 0<=i<c:res.ap                Pend ([r0,i]) Count + = 1 # print (count) # Print (res) Direction = 4 Continue if direction = = 4:r0 = L # print (' d Irection:4,pos: ', r0,c0) for I in Range (r0+l-1,r0-1,-1): If 0<=i<r and 0<=c0<                C:res.append ([i,c0]) Count + = 1 # print (count) # Print (res) Direction = 1 L + = 1 Continue return res

Each conversion direction, each walk two times the length plus 1, the loop jumps out the condition for the quantity to reach all the lattice number. For each walk, the judgment is preserved within the range of the board.

885. Spiral Matrix III