LeetCode(657)Judge Route Circle
阿新 • • 發佈:2019-01-10
題目
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
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
分析
題意判斷機器人能否按照給定的行走方向回到原點。
前進共有4個選擇:U,D,L,R;
只需求出每個方向的前進步數,判斷U==D,且L==R即可。
程式碼
class Solution { public boolean judgeCircle(String moves) { if (moves.isEmpty()) { return true; } int countU = 0, countD = 0, countL = 0, countR = 0, len = moves.length(); for (int i = 0; i < len; ++i) { char c = moves.charAt(i); switch (c) { case 'U': ++countU; break; case 'D': ++countD; break; case 'L': ++countL; break; case 'R': ++countR; break; default: return false; } } return countD == countU && countL == countR; } }