feat: add solutions to lc problems: No.0817, 1715

Author: yanglbme

solution/0800-0899/0817.Linked List Components/README.md

@@ -43,27 +43,83 @@ G = [0, 3, 1, 4]
 	<li><code>G</code> 是链表中所有结点的值的一个子集.</li>
 </ul>
 
-
 ## 解法
 
 <!-- 这里可写通用的实现逻辑 -->
 
+定义 pre 表示是否可加 1，初始为 true。
+
+遍历链表各个结点：
+
+- 若当前结点值在 nums 中，并且当前为可加 1 的状态，则 `res++`，并且将 pre 状态置为 false；
+- 若当前结点值不在 nums 中，则将 pre 置为 true，表示可加 1。
+
+最后返回 res 即可。
+
 <!-- tabs:start -->
 
 ### **Python3**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
+class Solution:
+    def numComponents(self, head: ListNode, nums: List[int]) -> int:
+        s = set(nums)
+        res, pre = 0, True
+        while head:
+            if head.val in s:
+                if pre:
+                    res += 1
+                    pre = False
+            else:
+                pre = True
+            head = head.next
+        return res
 ```
 
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
-
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+    public int numComponents(ListNode head, int[] nums) {
+        Set<Integer> s = new HashSet<>();
+        for (int num : nums) {
+            s.add(num);
+        }
+        int res = 0;
+        boolean pre = true;
+        while (head != null) {
+            if (s.contains(head.val)) {
+                if (pre) {
+                    ++res;
+                    pre = false;
+                }
+            } else {
+                pre = true;
+            }
+            head = head.next;
+        }
+        return res;
+    }
+}
 ```
 
 ### **...**

solution/0800-0899/0817.Linked List Components/README_EN.md

@@ -6,20 +6,12 @@
 
 <p>We are given&nbsp;<code>head</code>,&nbsp;the head node of a linked list containing&nbsp;<strong>unique integer values</strong>.</p>
 
-
-
 <p>We are also given the list&nbsp;<code>G</code>, a subset of the values in the linked list.</p>
 
-
-
 <p>Return the number of connected components in <code>G</code>, where two values are connected if they appear consecutively in the linked list.</p>
 
-
-
 <p><strong>Example 1:</strong></p>
 
-
-
 <pre>
 
 <strong>Input:</strong> 
@@ -36,12 +28,8 @@ G = [0, 1, 3]
 
 </pre>
 
-
-
 <p><strong>Example 2:</strong></p>
 
-
-
 <pre>
 
 <strong>Input:</strong> 
@@ -58,35 +46,77 @@ G = [0, 3, 1, 4]
 
 </pre>
 
-
-
 <p><strong>Note: </strong></p>
 
-
-
 <ul>
 	<li>If&nbsp;<code>N</code>&nbsp;is the&nbsp;length of the linked list given by&nbsp;<code>head</code>,&nbsp;<code>1 &lt;= N &lt;= 10000</code>.</li>
 	<li>The value of each node in the linked list will be in the range<code> [0, N - 1]</code>.</li>
 	<li><code>1 &lt;= G.length &lt;= 10000</code>.</li>
 	<li><code>G</code> is a subset of all values in the linked list.</li>
 </ul>
 
-
-
 ## Solutions
 
 <!-- tabs:start -->
 
 ### **Python3**
 
 ```python
-
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
+class Solution:
+    def numComponents(self, head: ListNode, nums: List[int]) -> int:
+        s = set(nums)
+        res, pre = 0, True
+        while head:
+            if head.val in s:
+                if pre:
+                    res += 1
+                    pre = False
+            else:
+                pre = True
+            head = head.next
+        return res
 ```
 
 ### **Java**
 
 ```java
-
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+    public int numComponents(ListNode head, int[] nums) {
+        Set<Integer> s = new HashSet<>();
+        for (int num : nums) {
+            s.add(num);
+        }
+        int res = 0;
+        boolean pre = true;
+        while (head != null) {
+            if (s.contains(head.val)) {
+                if (pre) {
+                    ++res;
+                    pre = false;
+                }
+            } else {
+                pre = true;
+            }
+            head = head.next;
+        }
+        return res;
+    }
+}
 ```
 
 ### **...**

solution/0800-0899/0817.Linked List Components/Solution.java

@@ -3,36 +3,30 @@
  * public class ListNode {
  *     int val;
  *     ListNode next;
- *     ListNode(int x) { val = x; }
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
  * }
  */
 class Solution {
-    public int numComponents(ListNode head, int[] G) {
-        if (head == null || G == null) {
-            return 0;
+    public int numComponents(ListNode head, int[] nums) {
+        Set<Integer> s = new HashSet<>();
+        for (int num : nums) {
+            s.add(num);
         }
-        Set<Integer> set = new HashSet<>();
-        for (int val : G) {
-            set.add(val);
-        }
-        int n = G.length;
-        ListNode cur = head;
-        int cnt = 0;
-        boolean flag = false;
-        while (cur != null) {
-            while (cur != null && set.contains(cur.val)) {
-                flag = true;
-                cur = cur.next;
-            }
-            if (flag) {
-                ++cnt;
-                flag = false;
-            }
-            
-            if (cur != null) {
-                cur = cur.next;
+        int res = 0;
+        boolean pre = true;
+        while (head != null) {
+            if (s.contains(head.val)) {
+                if (pre) {
+                    ++res;
+                    pre = false;
+                }
+            } else {
+                pre = true;
             }
+            head = head.next;
         }
-        return cnt;
+        return res;
     }
 }

solution/0800-0899/0817.Linked List Components/Solution.py

@@ -1,29 +1,18 @@
 # Definition for singly-linked list.
 # class ListNode:
-#     def __init__(self, x):
-#         self.val = x
-#         self.next = None
-
-
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
 class Solution:
-    def numComponents(self, head, G):
-        """
-        :type head: ListNode
-        :type G: List[int]
-        :rtype: int
-        """
-        dic = set(G)
-        ans = 0
-        flag = 0
+    def numComponents(self, head: ListNode, nums: List[int]) -> int:
+        s = set(nums)
+        res, pre = 0, True
         while head:
-            if head.val not in dic:
-                if flag == 1:
-                    ans += 1
-                    flag = 0
+            if head.val in s:
+                if pre:
+                    res += 1
+                    pre = False
             else:
-                flag = 1
+                pre = True
             head = head.next
-        else:
-            if flag == 1:
-                ans += 1
-        return ans
+        return res

solution/1700-1799/1715.Count Apples and Oranges/README.md

@@ -90,12 +90,23 @@ Chests 表：
 
 <!-- 这里可写通用的实现逻辑 -->
 
+“`LEFT JOIN` + `IFNULL`”实现。
+
 <!-- tabs:start -->
 
 ### **SQL**
 
 ```sql
-
+# Write your MySQL query statement below
+SELECT
+    SUM(IFNULL(b.apple_count, 0) + IFNULL(c.apple_count, 0)) AS apple_count,
+    SUM(IFNULL(b.orange_count, 0) + IFNULL(c.orange_count, 0)) AS orange_count
+FROM
+    Boxes b
+LEFT JOIN
+    Chests c
+ON
+    b.chest_id = c.chest_id;
 ```
 
 <!-- tabs:end -->

solution/1700-1799/1715.Count Apples and Oranges/README_EN.md

@@ -93,10 +93,21 @@ Total number of oranges = 15 + 25 + 8 + 28 + 15 + 15 + 17 = 123
 
 <!-- tabs:start -->
 
+`LEFT JOIN` and `IFNULL`.
+
 ### **SQL**
 
 ```sql
-
+# Write your MySQL query statement below
+SELECT
+    SUM(IFNULL(b.apple_count, 0) + IFNULL(c.apple_count, 0)) AS apple_count,
+    SUM(IFNULL(b.orange_count, 0) + IFNULL(c.orange_count, 0)) AS orange_count
+FROM
+    Boxes b
+LEFT JOIN
+    Chests c
+ON
+    b.chest_id = c.chest_id;
 ```
 
 <!-- tabs:end -->

solution/1700-1799/1715.Count Apples and Oranges/Solution.sql

@@ -0,0 +1,10 @@
+# Write your MySQL query statement below
+SELECT
+    SUM(IFNULL(b.apple_count, 0) + IFNULL(c.apple_count, 0)) AS apple_count,
+    SUM(IFNULL(b.orange_count, 0) + IFNULL(c.orange_count, 0)) AS orange_count
+FROM
+    Boxes b
+LEFT JOIN
+    Chests c
+ON
+    b.chest_id = c.chest_id;