657. Judge Route Circle

最新推荐文章于 2021-02-14 19:40:03 发布

原创最新推荐文章于 2021-02-14 19:40:03 发布 · 191 阅读

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本文介绍了一个简单的算法，用于判断机器人在给定移动序列后是否能回到起点。通过计算水平和垂直偏移量，可以快速确定机器人是否完成了一圈。

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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 represented 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

这个题很简单，就是判断各种拐弯时候能不能绕回来。直接上代码吧。

class Solution {
public:
    bool judgeCircle(string moves) {
        if (moves.length() == 0) return true;
        if (moves.length() % 2 == 1) return false;
        int offset_x = 0;
        int offset_y = 0;
        for (int i = 0; i < moves.length(); i++) {
            if (moves[i] == 'U') {
                offset_y++;
            } else if (moves[i] == 'D') {
                offset_y--;
            } else if (moves[i] == 'L') {
                offset_x--;
            } else if (moves[i] == 'R') {
                offset_x++;
            } else {
                i++;
            }
        }
        return offset_x == 0 && offset_y == 0 ? true : false;
    }
};