docs: add last stone weight description algorithm

Author: bujosa

alternative/easy/last_stone_weight.py

@@ -12,4 +12,18 @@ def lastStoneWeight(stones: List[int]) -> int:
             heapq.heappush(maxHeap, -(stone1 - stone2))
     return -maxHeap[0] if maxHeap else 0
 
-assert lastStoneWeight([2,7,4,1,8,1]) == 1
+assert lastStoneWeight([2,7,4,1,8,1]) == 1
+
+# Algorithm - Max Heap
+# Time Complexity - O(nlogn)
+# Space Complexity - O(n)
+
+# Description
+
+# 1. Initialize a maxHeap
+# 2. For each stone in stones, push the negative stone to the maxHeap
+# 3. While the length of the maxHeap is greater than 1:
+# 4. Pop the maxHeap and assign it to stone1
+# 5. Pop the maxHeap and assign it to stone2
+# 6. If stone1 is not equal to stone2, push the difference of stone1 and stone2 to the maxHeap
+# 7. Return the negative of the maxHeap[0] if the maxHeap is not empty, otherwise return 0