add 1046

fishercoder1534 · fishercoder1534 · commit ffef45899eb9 · 2019-12-22T17:57:26.000-08:00
diff --git a/README.md b/README.md
@@ -58,6 +58,7 @@ _If you like this project, please leave me a star._ &#9733;
 |1055|[Fixed Point](https://leetcode.com/problems/fixed-point/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1055.java) |  |Easy||
 |1051|[Height Checker](https://leetcode.com/problems/height-checker/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1051.java) | |Easy||
 |1047|[Remove All Adjacent Duplicates In String](https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1047.java) | |Easy||
+|1046|[Last Stone Weight](https://leetcode.com/problems/last-stone-weight/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1046.java) | |Easy||
 |1043|[Partition Array for Maximum Sum](https://leetcode.com/problems/partition-array-for-maximum-sum/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1043.java) |  |Medium|DP|
 |1038|[Binary Search Tree to Greater Sum Tree](https://leetcode.com/problems/binary-search-tree-to-greater-sum-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1038.java) | |Medium|DFS, tree|
 |1037|[Valid Boomerang](https://leetcode.com/problems/valid-boomerang/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1037.java) | |Easy|Math|
diff --git a/src/main/java/com/fishercoder/solutions/_1046.java b/src/main/java/com/fishercoder/solutions/_1046.java
@@ -0,0 +1,50 @@
+package com.fishercoder.solutions;
+
+import java.util.PriorityQueue;
+
+/**
+ * 1046. Last Stone Weight
+ *
+ * We have a collection of rocks, each rock has a positive integer weight.
+ *
+ * Each turn, we choose the two heaviest rocks and smash them together.
+ * Suppose the stones have weights x and y with x <= y.  The result of this smash is:
+ *
+ * If x == y, both stones are totally destroyed;
+ * If x != y, the stone of weight x is totally destroyed, and the stone of weight y has new weight y-x.
+ * At the end, there is at most 1 stone left.  Return the weight of this stone (or 0 if there are no stones left.)
+ *
+ * Example 1:
+ * Input: [2,7,4,1,8,1]
+ * Output: 1
+ * Explanation:
+ * We combine 7 and 8 to get 1 so the array converts to [2,4,1,1,1] then,
+ * we combine 2 and 4 to get 2 so the array converts to [2,1,1,1] then,
+ * we combine 2 and 1 to get 1 so the array converts to [1,1,1] then,
+ * we combine 1 and 1 to get 0 so the array converts to [1] then that's the value of last stone.
+ *
+ * Note:
+ * 1 <= stones.length <= 30
+ * 1 <= stones[i] <= 1000
+ * */
+public class _1046 {
+    public static class Solution1 {
+        public int lastStoneWeight(int[] stones) {
+            PriorityQueue<Integer> heap = new PriorityQueue<>((a, b) -> b - a);
+            for (int stone : stones) {
+                heap.offer(stone);
+            }
+            while (!heap.isEmpty()) {
+                if (heap.size() >= 2) {
+                    int one = heap.poll();
+                    int two = heap.poll();
+                    int diff = one - two;
+                    heap.offer(diff);
+                } else {
+                    return heap.poll();
+                }
+            }
+            return -1;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_1046Test.java b/src/test/java/com/fishercoder/_1046Test.java
@@ -0,0 +1,21 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1046;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static junit.framework.Assert.assertEquals;
+
+public class _1046Test {
+    private static _1046.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1046.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(1, solution1.lastStoneWeight(new int[]{2, 7, 4, 1, 8, 1}));
+    }
+}
