原题链接在这里:https://leetcode.com/problems/judge-route-circle/description/
题目:
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
(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
题解:
判断'U'和'D' && 'R'和 'L'的个数是否相同.
Time Complexity: O(moves.length()). Space: O(1).
AC Java:
class Solution {
public boolean judgeCircle(String moves) {
int x = 0;
int y = 0;
for(int i = 0; i<moves.length(); i++){
char c = moves.charAt(i);
if(c == 'U'){
y++;
}else if(c == 'D'){
y--;
}else if(c == 'R'){
x++;
}else if(c == 'L'){
x--;
}
}
return x==0 && y==0;
}
}