Merge pull request chipbk10#113 from chipbk10/Heap

Solve Problem 1046 - Last Stone Weight

Author: chipbk10

src/heap/Problem1046_LastStoneWeight.java

@@ -0,0 +1,46 @@
+package heap;
+
+import java.util.PriorityQueue;
+
+public class Problem1046_LastStoneWeight {
+
+    public int lastStoneWeight(int[] A) {
+        int B[] = new int[1001], i = 1000;
+        for (int a : A) B[a]++;
+
+        int j = 0;
+        while (i >= 0) {
+
+            while (i >= 0 && B[i] == 0) i--;
+            if (i >= 0 && B[i] != 0) {
+                System.out.println(i);
+                j = i;
+                B[i]--;
+            }
+
+            while (i >= 0 && B[i] != 0) i--;
+            if (i >= 0 && B[i] != 0) {
+                System.out.println(i);
+                j -= i;
+                B[i]--;
+                B[j]++;
+                i = Math.max(i, j);
+            }
+        }
+
+        return j;
+    }
+
+    public int lastStoneWeight_usingHeap(int[] A) {
+        PriorityQueue<Integer> pq = new PriorityQueue<>((a, b) -> b-a);
+        for (int a : A) pq.offer(a);
+        while (!pq.isEmpty()) {
+            int a = pq.poll();
+            if (pq.isEmpty()) return a;
+            int b = pq.poll();
+            if (a > b) pq.offer(a-b);
+        }
+        return 0;
+    }
+
+}