map的一些写法思考

src/main/java/com/ximo/datastructuresinaction/leetcode/solution349/Solution.java

@@ -0,0 +1,26 @@
+package com.ximo.datastructuresinaction.leetcode.solution349;
+
+import java.util.Arrays;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+/**
+ * @author xikl
+ * @date 2018/12/28
+ */
+public class Solution {
+
+
+    public int[] intersection(int[] nums1, int[] nums2) {
+        Set<Integer> set1 = Arrays.stream(nums1).boxed().collect(Collectors.toSet());
+        Set<Integer> set2 = Arrays.stream(nums2).boxed().collect(Collectors.toSet());
+
+        set1.retainAll(set2);
+
+
+        return set1.stream().mapToInt(Integer::intValue).toArray();
+    }
+
+
+
+}

src/main/java/com/ximo/datastructuresinaction/leetcode/solution350/Solution.java

@@ -0,0 +1,51 @@
+package com.ximo.datastructuresinaction.leetcode.solution350;
+
+
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * @author xikl
+ * @date 2018/12/28
+ */
+public class Solution {
+
+    public int[] intersection(int[] nums1, int[] nums2) {
+        Map<Integer, Integer> map = new HashMap<>();
+
+        for (int num : nums1) {
+//            if (!map.containsKey(num)) {
+//                map.put(num, 1);
+//            } else {
+//                map.put(num, map.get(num) + 1);
+//            }
+
+            map.compute(num, (key, value) -> value == null ? 1 : value + 1);
+        }
+
+        List<Integer> list = new LinkedList<>();
+        for (int num : nums2) {
+//            if (map.containsKey(num)) {
+//                list.add(num);
+//                map.put(num, map.get(num) - 1);
+//                if (map.get(num) == 0) {
+//                    map.remove(num);
+//                }
+//            }
+            map.computeIfPresent(num, (key, value) -> {
+                list.add(key);
+                value = value - 1;
+                if (value == 0) {
+                    map.remove(key);
+                }
+                return value;
+            });
+        }
+
+        return list.stream().mapToInt(Integer::intValue).toArray();
+    }
+
+
+}

src/main/java/com/ximo/datastructuresinaction/leetcode/Solution804/Solution.java → src/main/java/com/ximo/datastructuresinaction/leetcode/solution804/Solution.java

@@ -1,4 +1,4 @@
-package com.ximo.datastructuresinaction.leetcode.Solution804;
+package com.ximo.datastructuresinaction.leetcode.solution804;
 
 import java.util.Set;
 import java.util.TreeSet;