LeetCode 657 - Judge Route Circle

问题描述

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

Related Topics: String

原问题: 657. Judge Route Circle

中文翻译版: 657. 判断路线成圈

解决方案

根据题目描述，可以设定一个二维坐标 (x, y)，根据指令做相应的改变：

• Right: x = x + 1
• Left: x = x - 1
• Up: y = y + 1
• Down: y = y - 1

最后判断二维坐标 (x, y) 是否为原点 (0, 0) 即可。实现代码如下：

#include <iostream>
using namespace std;

class Solution {
public:
    bool judgeCircle(string moves)
    {
        int x = 0, y = 0;

        for (int i=0; i<moves.size(); i++) {
            switch (moves[i]) {
                case 'U':
                    y++;
                    break;
                case 'D':
                    y--;
                    break;
                case 'L':
                    x--;
                    break;
                case 'R':
                    x++;
                    break;
            }
        }

        return (x == 0 && y == 0);
    }
};

int main()
{
    Solution solu;
    string str1 = "UD";
    cout << str1 << ": " << solu.judgeCircle(str1) << endl;
    string str2 = "LL";
    cout << str2 << ": " << solu.judgeCircle(str2) << endl;

    return 0;
}