add 657

Author: fishercoder1534

README.md

@@ -22,6 +22,7 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Difficulty  | Tag          | Notes
 |-----|----------------|---------------|---------------|---------------|-------------|--------------|-----
+|657|[Judge Route Circle](https://leetcode.com/problems/judge-route-circle/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_657.java) | O(n) | O(1) | Easy | 
 |654|[Maximum Binary Tree](https://leetcode.com/problems/maximum-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_654.java) | O(n^2) | O(n) | Medium | Tree
 |653|[Two Sum IV - Input is a BST](https://leetcode.com/problems/two-sum-iv-input-is-a-bst/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_653.java) |  |  | Easy | Tree
 |652|[Find Duplicate Subtrees](https://leetcode.com/problems/find-duplicate-subtrees/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_652.java) | O(n) |O(n) | Medium | Tree

src/main/java/com/fishercoder/solutions/_657.java

@@ -0,0 +1,41 @@
+package com.fishercoder.solutions;
+
+/**
+ * 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
+ */
+
+public class _657 {
+    public boolean judgeCircle(String moves) {
+        int hori = 0;
+        int verti = 0;
+        for (char c : moves.toCharArray()) {
+            if (c == 'U') {
+                verti++;
+            } else if (c == 'D') {
+                verti--;
+            } else if (c == 'L') {
+                hori--;
+            } else if (c == 'R') {
+                hori++;
+            }
+        }
+        return verti == 0 && hori == 0;
+    }
+}