Merge branch 'develop'

Author: kdgyun

DataStructure/Java/_09_Heap/Heap.java

@@ -166,7 +166,13 @@ public E remove() {
 			throw new NoSuchElementException();
 		}	
 		E result = (E) array[1]; 
-		E target = (E) array[size];
+		E target;
+		if(size == 1) {
+			target = null;
+		}
+		else {
+			target = (E) array[size];
+		}
 		array[size] = null;
 		size--;	
 		siftDown(1, target);	

DataStructure/Java/_10_PriorityQueue/PriorityQueue.java

@@ -194,7 +194,13 @@ public E remove() {
 		}	
 
 		E result = (E) array[1];
-		E target = (E) array[size];
+		E target;
+		if(size == 1) {
+			target = null;
+		}
+		else {
+			target = (E) array[size];
+		}
 
 		array[size] = null;
 		size--;