feat: add the solution of Baseball Game(682) with Java.

Author: Mukyu

README.md

@@ -72,7 +72,7 @@
 | [671][671-question] | [Second Minimum Node In a Binary Tree][671-tips]             | [✅][671-java] | [✅][671-js] |                  |
 | [674][674-question] | [Longest Continuous Increasing Subsequence][674-tips]        | [✅][674-java] | [✅][674-js] |                  |
 | [680][680-question] | [Valid Palindrome II][680-tips]                              | [✅][680-java] | [✅][680-js] |                  |
-| [682][682-question] | [Baseball Game][682-tips]                                    |                | [✅][682-js] |                  |
+| [682][682-question] | [Baseball Game][682-tips]                                    | [✅][682-java] | [✅][682-js] |                  |
 | [686][686-question] | [Repeated String Match][686-tips]                            |                | [✅][686-js] |                  |
 | [687][687-question] | [Longest Univalue Path][687-tips]                            |                | [✅][687-js] |                  |
 | [693][693-question] | [Binary Number with Alternating Bits][693-tips]              |                | [✅][693-js] |                  |
@@ -465,6 +465,7 @@
 [671-java]: ./src/_671/Solution.java
 [674-java]: ./src/_674/Solution.java
 [680-java]: ./src/_680/Solution.java
+[682-java]: ./src/_682/Solution.java
 [728-java]: ./src/_728/Solution.java
 [771-java]: ./src/_771/Solution.java
 [804-java]: ./src/_804/Solution.java

src/_682/Solution.java

@@ -0,0 +1,33 @@
+package _682;
+
+class Solution {
+    public int calPoints(String[] ops) {
+        int[] scores = new int[1000];
+        int sum = 0;
+        int i = 0;
+
+        for (String op : ops) {
+            if (op.charAt(0) == 'C') {
+                sum -= scores[i--];
+                continue;
+            }
+
+            i++;
+            if (op.charAt(0) == '+') {
+                scores[i] = scores[i-1] + scores[i-2];
+            } else if (op.charAt(0) == 'D') {
+                scores[i] = scores[i - 1] * 2;
+            } else {
+                scores[i] = Integer.valueOf(op);
+            }
+            sum += scores[i];
+        }
+
+        return sum;
+    }
+
+    public static void main(String[] args) {
+        Solution solution = new Solution();
+        System.out.println(solution.calPoints(new String[]{"5","-2","4","C","D","9","+","+"}));
+    }
+}

tips/682/README.md

@@ -1,46 +1,90 @@
-[xxxx][title]
+[Baseball Game][title]
 
 ## Description
-// 抄题目
 
+You're now a baseball game point recorder.
 
-**Example:**
+Given a list of strings, each string can be one of the 4 following types:
 
-```
-// 抄Example
-```
-
-**Note:**
-// Note
+1. `Integer` (one round's score): Directly represents the number of points you get in this round.
+2. `"+"` (one round's score): Represents that the points you get in this round are the sum of the last two `valid` round's points.
+3. `"D"` (one round's score): Represents that the points you get in this round are the doubled data of the last `valid` round's points.
+4. `"C"` (an operation, which isn't a round's score): Represents the last `valid` round's points you get were invalid and should be removed.
 
-**Tags:** // tags
+Each round's operation is permanent and could have an impact on the round before and the round after.
 
+You need to return the sum of the points you could get in all the rounds.
 
-## 思路 1
-// 贴一些关键代码,说一些解题思路
-// (同一种语言可以写多种思路，与某种语言思路相同的另一种语言的思路无须赘述，但可以把代码贴在后面) 
-```java
+**Example 1:**
 
 ```
-```javascript
-
+Input: ["5","2","C","D","+"]
+Output: 30
+Explanation: 
+Round 1: You could get 5 points. The sum is: 5.
+Round 2: You could get 2 points. The sum is: 7.
+Operation 1: The round 2's data was invalid. The sum is: 5.  
+Round 3: You could get 10 points (the round 2's data has been removed). The sum is: 15.
+Round 4: You could get 5 + 10 = 15 points. The sum is: 30.
 ```
 
-## 思路 2
-// 贴一些关键代码,说一些解题思路
-```java
+**Example 2:**
 
+```
+Input: ["5","-2","4","C","D","9","+","+"]
+Output: 27
+Explanation: 
+Round 1: You could get 5 points. The sum is: 5.
+Round 2: You could get -2 points. The sum is: 3.
+Round 3: You could get 4 points. The sum is: 7.
+Operation 1: The round 3's data is invalid. The sum is: 3.  
+Round 4: You could get -4 points (the round 3's data has been removed). The sum is: -1.
+Round 5: You could get 9 points. The sum is: 8.
+Round 6: You could get -4 + 9 = 5 points. The sum is 13.
+Round 7: You could get 9 + 5 = 14 points. The sum is 27.
 ```
 
-## 思路 3
-// 贴一些关键代码,说一些解题思路
-```kotlin
+**Note:**
+
+- The size of the input list will be between 1 and 1000.
+- Every integer represented in the list will be between -30000 and 30000.
+
+## 思路
+
+整数代表所得分数；`+`代表所得分数为最后两回合的有效分数的和；`D`代表所得分数为最后一回合的有效分数的两倍；`C`代表最后一回合的分数无效。按题意计算分数即可。
 
+**Java:**
+
+```java
+public int calPoints(String[] ops) {
+    int[] scores = new int[1000];
+    int sum = 0;
+    int i = 0;
+
+    for (String op : ops) {
+        if (op.charAt(0) == 'C') {
+            sum -= scores[i--];
+            continue;
+        }
+
+        i++;
+        if (op.charAt(0) == '+') {
+            scores[i] = scores[i-1] + scores[i-2];
+        } else if (op.charAt(0) == 'D') {
+            scores[i] = scores[i - 1] * 2;
+        } else {
+            scores[i] = Integer.valueOf(op);
+        }
+        sum += scores[i];
+    }
+
+    return sum;
+}
 ```
 
 ## 结语
-   
+
 如果你同我们一样热爱数据结构、算法、LeetCode，可以关注我们 GitHub 上的 LeetCode 题解：[LeetCode-Solution][ls]
 
-[title]: https://leetcode.com/problems/xxxx
+[title]: https://leetcode.com/problems/baseball-game/description/
 [ls]: https://github.com/SDE603/LeetCode-Solution