leetcode 657. Judge Route Circle

最新推荐文章于 2018-12-06 22:13:00 发布

huanghanqian

最新推荐文章于 2018-12-06 22:13:00 发布

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本文介绍了一个简单的算法问题，即如何判断一个机器人在执行一系列移动指令后是否回到了初始位置(0,0)。通过分析输入字符串中不同方向移动的次数，可以有效地确定机器人最终是否回到了起点。

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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 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

简单题一个。

public boolean judgeCircle(String moves) {
	//L放在int[0]，R放在int[1]
	//U放在int[2]，D放在int[3]
	int[] directions=new int[4];
	for(int i=0;i<moves.length();i++){
		char c=moves.charAt(i);
		switch (c) {
		case 'L':
			directions[0]++;
			break;
		case 'R':
			directions[1]++;
			break;
		case 'U':
			directions[2]++;
			break;
		case 'D':
		    directions[3]++;
		    break;
		}
	}
	if(directions[0]==directions[1]&&directions[2]==directions[3]){
		return true;
	}
	return false;
}

大神思路跟我一样，用了更加 clean 的 code。

public class Solution {
    public boolean judgeCircle(String moves) {
        int x = 0;
        int y = 0;
        for (char ch : moves.toCharArray()) {
            if (ch == 'U') y++;
            if (ch == 'D') y--;
            if (ch == 'R') x++;
            if (ch == 'L') x--;
        }
        return x == 0 && y == 0;
    }
}