From 92e7ac3d19c4c6aa73ff238d764b6a48e4a92183 Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Wed, 4 Sep 2024 21:43:13 +0200
Subject: [PATCH] =?UTF-8?q?java:=20add=20=C2=AB874.=20Walking=20Robot=20Si?=
 =?UTF-8?q?mulation=C2=BB?=
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Signed-off-by: Matej Focko <me@mfocko.xyz>
---
 java/walking-robot-simulation.java | 57 ++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 java/walking-robot-simulation.java

diff --git a/java/walking-robot-simulation.java b/java/walking-robot-simulation.java
new file mode 100644
index 0000000..7b0c3de
--- /dev/null
+++ b/java/walking-robot-simulation.java
@@ -0,0 +1,57 @@
+import java.util.HashSet;
+
+class Solution {
+  private static final int TURN_LEFT = -2;
+  private static final int TURN_RIGHT = -1;
+
+  private record Vec(int x, int y) {
+    public Vec turnLeft() {
+      return new Vec(-y, x);
+    }
+
+    public Vec turnRight() {
+      return new Vec(y, -x);
+    }
+
+    public Vec add(Vec other) {
+      return new Vec(x + other.x, y + other.y);
+    }
+
+    public int distance() {
+      return Math.abs(x * x + y * y);
+    }
+  }
+
+  public int robotSim(int[] commands, int[][] obstacles) {
+    int maxDistance = 0;
+
+    // Process obstacles
+    var uniqueObstacles = new HashSet<Vec>();
+    for (int[] obstacle : obstacles) {
+      uniqueObstacles.add(new Vec(obstacle[0], obstacle[1]));
+    }
+
+    var pos = new Vec(0, 0);
+    var direction = new Vec(0, 1);
+
+    for (int command : commands) {
+      if (command == TURN_LEFT) {
+        direction = direction.turnLeft();
+      } else if (command == TURN_RIGHT) {
+        direction = direction.turnRight();
+      }
+
+      for (var steps = 0; steps < command; ++steps) {
+        var next = pos.add(direction);
+        if (uniqueObstacles.contains(next)) {
+          break;
+        }
+
+        pos = next;
+        maxDistance = Math.max(maxDistance, pos.distance());
+      }
+    }
+
+    return maxDistance;
+  }
+}