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Leetcode 1041 Robot Bounded In Circle

· One min read

跟別人不同的解法紀錄一下...

prob. desc.​

  • 機器人可以無窮的做instructions
  • return 在不限instructions次數的情況下，機器人是否在某輪instructions執行的結尾回到原點

my sol.​

  • 紀錄座標(x, y)及面相(a, b)，其中 (a, b)表示複數a+bi
  • 計算一輪後的(x, y, a, b)
    • 回原點為 True
    • 沒回就考慮面向
      • 面向(a, b)沒變表示不可能回原點，return False
class Solution:

    def isRobotBounded(self, instructions: str) -> bool:
        #      x y a  bi
        mat = [0,0,0, 1]

        for i in instructions:
            if i =='G':
                mat[0] += mat[2]
                mat[1] += mat[3]

            elif i == 'L':
                mat[2], mat[3] = -mat[3], mat[2]
                # (a+bi) *i
                # = -b +ai

            elif i == 'R':
                mat[2], mat[3] = mat[3], -mat[2]
                # (a+bi) *i^3
                # = b -ai

        return mat[:2] == [0, 0] or mat[2:] != [0,1]

problem info​

https://leetcode.com/problems/robot-bounded-in-circle/