# 文档更新说明

• 最后更新 2018年03月08日
• 首次更新 2018年03月08日

# 前言

使用Swift语言完成LetCode题目,简单难度

# 771. Jewels and Stones

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.

## Example1

Input: "UD"
Output: true


## Example2

Input: "LL"
Output: false