算法第四周Judge Route Circle[easy]

Judge Route Circle[easy]

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Description

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

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Solution

这是一道十分容易的题目，机器人只有四个方向可以移动，如果最后能够回到原点，即为路线是环。那么何时回到原点？我们知道一上一下回到原点，一左一右回到原点，不难看出，如果上下的数目相等，并且左右的数目相等，那它一定会回到原点。

class Solution {public:    bool judgeCircle(string moves) {        int u = 0;        int d = 0;        int l = 0;        int r = 0;        for (int i = 0; i < moves.length(); i++) {            switch(moves[i]) {                  case 'U' : u++; break;                  case 'D' : d++; break;                  case 'L' : l++; break;                  case 'R' : r++; break;            }        }        if (u == d && l == r) {            return true;        } else {            return false;        }    }};