feat: add java solution to lc problem: NO.0731. My Calendar II (doocs#550)

Author: hongyiheng

solution/0700-0799/0731.My Calendar II/README.md

@@ -64,7 +64,30 @@ MyCalendar.book(25, 55); // returns true
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
-
+class MyCalendarTwo {
+    List<int[]> calendar;
+    List<int[]> duplicationList;
+
+    MyCalendarTwo() {
+        calendar = new ArrayList<>();
+        duplicationList = new ArrayList<>();
+    }
+
+    public boolean book(int start, int end) {
+        for (int[] item : duplicationList) {
+            if (item[0] < end && item[1] > start) {
+                return false;
+            }
+        }
+        for (int[] item : calendar) {
+            if (item[0] < end && item[1] > start) {
+                duplicationList.add(new int[]{Math.max(start, item[0]), Math.min(end, item[1])});
+            }
+        }
+        calendar.add(new int[]{start, end});
+        return true;
+    }
+}
 ```
 
 ### **...**

solution/0700-0799/0731.My Calendar II/README_EN.md

@@ -88,7 +88,30 @@ the time [40, 50) will be single booked, and the time [50, 55) will be double bo
 ### **Java**
 
 ```java
-
+class MyCalendarTwo {
+    List<int[]> calendar;
+    List<int[]> duplicationList;
+
+    MyCalendarTwo() {
+        calendar = new ArrayList<>();
+        duplicationList = new ArrayList<>();
+    }
+
+    public boolean book(int start, int end) {
+        for (int[] item : duplicationList) {
+            if (item[0] < end && item[1] > start) {
+                return false;
+            }
+        }
+        for (int[] item : calendar) {
+            if (item[0] < end && item[1] > start) {
+                duplicationList.add(new int[]{Math.max(start, item[0]), Math.min(end, item[1])});
+            }
+        }
+        calendar.add(new int[]{start, end});
+        return true;
+    }
+}
 ```
 
 ### **...**

solution/0700-0799/0731.My Calendar II/Solution.java

@@ -0,0 +1,24 @@
+class MyCalendarTwo {
+    List<int[]> calendar;
+    List<int[]> duplicationList;
+
+    MyCalendarTwo() {
+        calendar = new ArrayList<>();
+        duplicationList = new ArrayList<>();
+    }
+
+    public boolean book(int start, int end) {
+        for (int[] item : duplicationList) {
+            if (item[0] < end && item[1] > start) {
+                return false;
+            }
+        }
+        for (int[] item : calendar) {
+            if (item[0] < end && item[1] > start) {
+                duplicationList.add(new int[]{Math.max(start, item[0]), Math.min(end, item[1])});
+            }
+        }
+        calendar.add(new int[]{start, end});
+        return true;
+    }
+}