Solution to 1046

src/unresolved/1046.last-stone-weight.jl → src/problems/1046.last-stone-weight.jl

@@ -1,8 +1,8 @@
 # ---
 # title: 1046. Last Stone Weight
 # id: problem1046
-# author: Tian Jun
-# date: 2020-10-31
+# author: Queensley E
+# date: 2024-12-11
 # difficulty: Easy
 # categories: Heap, Greedy
 # link: <https://leetcode.com/problems/last-stone-weight/description/>
@@ -46,5 +46,31 @@
 ## @lc code=start
 using LeetCode
 
+using DataStructures
+
+function last_stone_weight(stones::Vector{Int64})
+    # Create a PriorityQueue with unique identifiers for each stone
+    heap = PriorityQueue{Tuple{Int64, Int64}, Int64}()
+    for (i, stone) in enumerate(stones)
+        enqueue!(heap, (stone, i), -stone)  # Use negative stone value for max-heap
+    end
+
+    while length(heap) > 1
+        # Extract the two largest stones
+        largest, _ = dequeue!(heap)
+        second_largest, _ = dequeue!(heap)
+
+        # If they are not the same, calculate the difference and enqueue it
+        if largest != second_largest
+            enqueue!(heap, (largest - second_largest, length(heap) + 1), -(largest - second_largest))
+        end
+    end
+
+    # Return the last stone or 0 if the heap is empty
+    return isempty(heap) ? 0 : first(first(collect(keys(heap))))
+end
+
+last_stone_weight([2, 7, 4, 1, 8, 2])
+
 ## add your code here:
 ## @lc code=end

test/problems/1046.last-stone-weight.jl

@@ -0,0 +1,12 @@
+using Test
+
+@testset "1046.last-stone-weight.jl" begin
+
+    @test last_stone_weight([2, 7, 4, 1, 8, 1]) == 1  # Problem example
+    @test last_stone_weight([1, 1]) == 0              # All stones cancel out
+    @test last_stone_weight([5]) == 5                # Single stone
+    @test last_stone_weight([10, 4, 3]) == 3         # Large differences
+    @test last_stone_weight([8, 8, 2, 2, 3]) == 1    # Mixed case
+    @test last_stone_weight([7, 6, 7, 6]) == 0       # Multiple canceling pairs
+
+end