class Solution(object):

def spiralMatrixIII(self, R, C, r0, c0):

ans = [(r0, c0)]

if R * C == 1:

return ans

# For walk length k = 1, 3, 5 ...

for k in range(1, 2*(R+C), 2):

# For direction (dr, dc) = east, south, west, north;

# and walk length dk...

for dr, dc, dk in ((0, 1, k), (1, 0, k), (0, -1, k+1), (-1, 0, k+1)):

# For each of dk units in the current direction ...

for _ in range(dk):

# Step in that direction

r0 += dr

c0 += dc

# If on the grid ...

if 0 <= r0 < R and 0 <= c0 < C:

ans.append((r0, c0))

if len(ans) == R * C:

return ans

print(Solution().spiralMatrixIII(5,6,1,4))