class Solution:
    def minSideJumps(self, obstacles: List[int]) -> int:
        #TC: O(n)
        #SC: O(n) easy to optimized to O(1)
        n = len(obstacles)
        dp = [[0]*3 for i in range(n)]

        dp[0][0] = 1
        dp[0][1] = 0
        dp[0][2] = 1

        for i in range(1,n):
            if obstacles[i] == 0:
                dp[i][0] = min(min(dp[i-1][1], dp[i-1][2])+1, dp[i-1][0])
                dp[i][1] = min(min(dp[i-1][0], dp[i-1][2])+1, dp[i-1][1])
                dp[i][2] = min(min(dp[i-1][0], dp[i-1][1])+1, dp[i-1][2])
            elif obstacles[i] == 1:
                dp[i][0] = sys.maxsize
                dp[i][1] = min(dp[i-1][2]+1, dp[i-1][1])
                dp[i][2] = min(dp[i-1][1]+1, dp[i-1][2])
            elif obstacles[i] == 2:
                dp[i][1] = sys.maxsize
                dp[i][0] = min(dp[i-1][2]+1, dp[i-1][0])
                dp[i][2] = min(dp[i-1][0]+1, dp[i-1][2])
            elif obstacles[i] == 3:
                dp[i][2] = sys.maxsize
                dp[i][0] = min(dp[i-1][1]+1, dp[i-1][0])
                dp[i][1] = min(dp[i-1][0]+1, dp[i-1][1])

        return min(dp[-1])