[LeetCode] 657.Judge Route Circle

• 题目描述
• 解题思路
• 实验代码

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题目描述

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

解题思路

题目的意思已经非常清楚了，不管怎么走，只要最后走到它开始的地方，那就算一个circle。那么就记录下它每走一步的坐标，如果最后的坐标和原坐标相同，则返回true，否则返回false。且它输入的字符只可能是“U”、“D”、“L”、“R”四个中的一个，问题就更简单了。具体见代码。

实验代码

class Solution {public:    bool judgeCircle(string moves) {        int x = 0, y = 0, l = moves.length();        for (int i = 0; i < l; i++) {            if (moves[i] == 'R') x++;            else if (moves[i] == 'L') x--;            else if (moves[i] == 'U') y++;            else if (moves[i] == 'D') y--;        }        if (x == 0 && y == 0) return true;        return false;    }};