[LeetCode] 657.Judge Route Circle

最新推荐文章于 2018-12-06 22:13:00 发布

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本文介绍了一种通过分析机器人移动序列来判断其是否回到初始位置的方法。利用简单的坐标记录技巧，实现了高效的判断逻辑。

[LeetCode] 657.Judge Route Circle

题目描述
解题思路
实验代码

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;
    }
};