657. Judge Route Circle

Problem Statement

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: trueExample 2:Input: "LL"Output: false

Thinking

这个题比较简单，心中有一个坐标系就可以。

Solution

class Solution {    public boolean judgeCircle(String moves) {        int x = 0,y = 0;        for(int i = 0; i < moves.length();i++)        {            if(moves.charAt(i) == 'U')                y++;            if(moves.charAt(i) == 'D')                y--;            if(moves.charAt(i) == 'R')                x++;            if(moves.charAt(i) == 'L')                x--;        }        if(x == 0 && y ==0)            return true;        else            return false;    }}