657. Judge Route Circle
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
题目大概的意思是有个机器人,给定一些列动作判断它最后回到原点没。
思路很简单,回到原点换个话说就是R和L操作数量一样,U和D操作数一样即可。
public class judgeCircle { public static boolean judgeCircle(String moves) { if(moves!=null&&moves.length()>0) { int ud=0; int lr=0; for(int i=0;i<moves.length();i++) { if(moves.charAt(i)=='U') { ud++; } if(moves.charAt(i)=='D') { ud--; } if(moves.charAt(i)=='L') { lr++; } if(moves.charAt(i)=='R') { lr--; } } if(ud==0&&lr==0) { return true; } else { return false; } } else { return false; } } public static void main(String args[]) { System.out.println(judgeCircle("UD")); } }