[update]

Author: Dream

algorithms/maximumProductOfTwoElementsInAnArray_Dream/maximumProductOfTwoElementsInAnArray_Dream.java

@@ -0,0 +1,49 @@
+import java.util.*;
+import java.util.stream.Collectors;
+
+/**
+ * @author Dream
+ */
+public class maximumProductOfTwoElementsInAnArray_Dream {
+    //研究了arrays.sort方法写的
+    class Solution1 {
+        public int maxProduct(int[] nums) {
+            for (int i = 0, j = i; i < nums.length - 1; j = ++i) {
+                int ai = nums[i + 1];
+                while (nums[j] < ai) {
+                    nums[j + 1] = nums[j];
+                    if (j-- == 0) {
+                        break;
+                    }
+                }
+                nums[j + 1] = ai;
+            }
+            return ((nums[0] - 1) * (nums[1] - 1));
+        }
+    }
+
+    //两次遍历取出最大值，并删除
+    class Solution2 {
+        public int maxProduct(int[] nums) {
+            Map<Integer, Integer> map = new HashMap<>(2);
+            map.put(0,0);
+            map.put(1,0);
+            List<Integer> collect = Arrays.stream(nums).boxed().collect(Collectors.toList());
+            foreachListToRemove(collect, map, 0);
+            foreachListToRemove(collect, map, 1);
+            return (map.get(0) - 1) * (map.get(1) - 1);
+        }
+
+        public void foreachListToRemove(List<Integer> collection,Map<Integer,Integer> map,Integer index) {
+            Iterator<Integer> iterator = collection.iterator();
+            while (iterator.hasNext()) {
+                Integer value = iterator.next();
+                if (map.get(index) < value) {
+                    map.put(index, value);
+                }
+            }
+            collection.remove(map.get(index));
+        }
+    }
+
+}

algorithms/uniqueNumberOfOccurrences/uniqueNumberOfOccurrences.java

@@ -1,5 +1,10 @@
+import java.util.HashMap;
+import java.util.Map;
 
-class Solution {
+/**
+ * @author Dream
+ */
+public class uniqueNumberOfOccurrences {
     public boolean uniqueOccurrences(int[] arr) {
         Map<Integer, Integer> map = new HashMap(arr.length);
         for(int i : arr){
@@ -15,4 +20,5 @@ public boolean uniqueOccurrences(int[] arr) {
         }
         return true;
     }
-}
+
+}