186th Commit

README.md

@@ -142,10 +142,11 @@ Ace Coding Interview with 75 Qs
 | Stack                              |                  |        |
 | ---------------------------------- | ---------------- | ------ |
 | 2390. Removing Stars From a String | [Solution][2390] | Medium |
-| 735. Asteroid Collision            | Solution         | Medium |
+| 735. Asteroid Collision            | [Solution][735]  | Medium |
 | 394. Decode String                 | Solution         | Medium |
 
 [2390]: ./src/page-22/2390.%20Removing%20Stars%20From%20a%20String/removeStars.ts
+[735]: ./src/page-7/735.%20Asteroid%20Collision/asteroidCollision.ts
 
 | Queue                       |          |        |
 | --------------------------- | -------- | ------ |

src/page-7/735. Asteroid Collision/asteroidCollision.test.ts

@@ -0,0 +1,9 @@
+import { asteroidCollision } from './asteroidCollision';
+
+describe('735. Asteroid Collision', () => {
+  test('asteroidCollision', () => {
+    expect(asteroidCollision([5, 10, -5])).toStrictEqual([5, 10]);
+    expect(asteroidCollision([8, -8])).toStrictEqual([]);
+    expect(asteroidCollision([10, 2, -5])).toStrictEqual([10]);
+  });
+});

src/page-7/735. Asteroid Collision/asteroidCollision.ts

@@ -0,0 +1,43 @@
+type AsteroidCollision = (asteroids: number[]) => number[];
+
+/**
+ * Accepted
+ */
+export const asteroidCollision: AsteroidCollision = (asteroids) => {
+  // Stack to keep track of the remaining asteroids after collisions
+  const stack: number[] = [];
+
+  // Iterate over each asteroid in the input array
+  for (const asteroid of asteroids) {
+    // A flag to determine whether the current asteroid is to be added to the stack
+    let addAsteroid = true;
+
+    // Handle collision scenarios only if the stack is not empty and
+    // the current asteroid is moving left (negative) while the top of the stack is moving right (positive)
+    while (stack.length > 0 && stack[stack.length - 1] > 0 && asteroid < 0) {
+      const topAsteroid = stack[stack.length - 1];
+
+      // Check if the top asteroid is larger, if so, the current asteroid explodes
+      if (Math.abs(topAsteroid) > Math.abs(asteroid)) {
+        addAsteroid = false;
+        break;
+      }
+
+      // Check if both asteroids are of the same size, both explode
+      if (Math.abs(topAsteroid) === Math.abs(asteroid)) {
+        stack.pop();
+        addAsteroid = false;
+        break;
+      }
+
+      // If the top asteroid is smaller, it explodes
+      stack.pop();
+    }
+
+    // If the current asteroid survives the collisions, add it to the stack
+    if (addAsteroid) stack.push(asteroid);
+  }
+
+  // Return the state of the asteroids after all collisions
+  return stack;
+};