Robot starting location

Author: edignot

README.md

@@ -46,6 +46,9 @@ There might still be some personal comments added for my learning purposes.
 [`Test file`](https://github.com/edignot/algorithm-data-structure-practice/blob/master/src/integer-to-roman/integer-to-roman.test.js)
 
 - **All**
+    * Robot Return to Origin
+[`Solution`](https://github.com/edignot/algorithm-data-structure-practice/blob/master/src/robot/robot.js) 
+[`Test file`](https://github.com/edignot/algorithm-data-structure-practice/blob/master/src/robot/robot.test.js)
     * Snail
 [`Solution`](https://github.com/edignot/algorithm-data-structure-practice/blob/master/src/snail/snail.js) 
 [`Test file`](https://github.com/edignot/algorithm-data-structure-practice/blob/master/src/snail/snail.test.js)

src/robot/robot.js

@@ -0,0 +1,36 @@
+// Problem: The robot moves on an plane, and its movements are described by a command string consisting of one or more of the following letters.
+// - G instructs the robot to move forward one step
+// - L instructs the robot to turn left
+// - R instructs the robot to turn right
+// The robot cannot go backwards. After running all of the movement commands, check if robot returns to the starting location.
+// Time complexity: O(n)
+
+function checkRobotLocation(str) {
+    const operation = str.split("");
+    let x = 0;
+    let y = 0;
+    let directions = ["N", "E", "S", "W"];
+    let direction = directions[0];
+
+    operation.forEach((task) => {
+        if (task === "G") {
+            direction === "N" && (y += 1);
+            direction === "S" && (y -= 1);
+            direction === "E" && (x += 1);
+            direction === "W" && (x -= 1);
+        } else if (task === "R") {
+            let i = directions.indexOf(direction);
+            directions.length <= i + 1
+                ? (direction = directions[0])
+                : (direction = directions[i + 1]);
+        } else if (task === "L") {
+            let i = directions.indexOf(direction);
+            i > 0
+                ? (direction = directions[i - 1])
+                : (direction = directions[directions.length - 1]);
+        }
+    });
+    return x === 0 && y === 0 ? true : false;
+}
+
+export default checkRobotLocation;

src/robot/robot.test.js

@@ -0,0 +1,13 @@
+import checkRobotLocation from "./robot";
+
+describe("Check if robot comes back to the original location", () => {
+    test("Check if robot comes back to the original location", () => {
+        expect(checkRobotLocation("GRGRGRG")).toBe(true);
+    });
+    test("Check if robot comes back to the original location", () => {
+        expect(checkRobotLocation("GRGLGLGLGG")).toBe(true);
+    });
+    test("Check if robot comes back to the original location", () => {
+        expect(checkRobotLocation("GRGLGGGLGLGG")).toBe(false);
+    });
+});