题目
Initially, there is a Robot at position (0, 0). Given a sequence of its moves, judge if this robot makes a circle, which means it moves back to the original place.
The move sequence is represented by a string. And each move is represent by a character. The valid robot moves are R(Right), L(Left), U(Up) and D(down). The output should be true or false representing whether the robot makes a circle.
Example 1:
Input: "UD"
Output: true
Example 2:
Input: "LL"
Output: false
难度
Easy
方法
对每个方向计数，如果L出现的次数==R出现的次数，并且U出现的次数==D出现的次数，则robot会回到初始位置，返回True；否则返回False
python代码
class Solution(object):
def judgeCircle(self, moves):
"""
:type moves: str
:rtype: bool
"""
counter = {}
for c in moves:
counter[c] = counter.get(c, 0) + 1
return counter.get("L") == counter.get("R") and counter.get("U") == counter.get("D")
assert Solution().judgeCircle("UD") == True
assert Solution().judgeCircle("LL") == False
