一刷228

Author: diguage

README.adoc

@@ -1622,13 +1622,13 @@ TIP: **公众号的微信号是: `jikerizhi`**。__因为众所周知的原因
 |Medium
 |
 
-//|{counter:codes}
-//|{leetcode_base_url}/summary-ranges/[228. Summary Ranges^]
-//|{source_base_url}/_0228_SummaryRanges.java[Java]
-//|{doc_base_url}/0228-summary-ranges.adoc[题解]
-//|Medium
-//|
-//
+|{counter:codes}
+|{leetcode_base_url}/summary-ranges/[228. Summary Ranges^]
+|{source_base_url}/_0228_SummaryRanges.java[Java]
+|{doc_base_url}/0228-summary-ranges.adoc[题解]
+|Medium
+|
+
 //|{counter:codes}
 //|{leetcode_base_url}/majority-element-ii/[229. Majority Element II^]
 //|{source_base_url}/_0229_MajorityElementII.java[Java]

docs/0000-06-two-pointer.adoc

@@ -43,6 +43,7 @@
 . xref:0186-reverse-words-in-a-string-ii.adoc[186. Reverse Words in a String II]
 . xref:0189-rotate-array.adoc[189. Rotate Array]
 . xref:0202-happy-number.adoc[202. Happy Number]
+. xref:0228-summary-ranges.adoc[228. Summary Ranges]
 . xref:0234-palindrome-linked-list.adoc[234. Palindrome Linked List]
 . xref:0244-shortest-word-distance-ii.adoc[244. Shortest Word Distance II]
 . xref:0246-strobogrammatic-number.adoc[246. Strobogrammatic Number]

docs/0228-summary-ranges.adoc

@@ -1,33 +1,77 @@
 [#0228-summary-ranges]
-= 228. Summary Ranges
+= 228. 汇总区间
 
-{leetcode}/problems/summary-ranges/[LeetCode - Summary Ranges^]
+https://leetcode.cn/problems/summary-ranges/[LeetCode - 228. 汇总区间 ^]
 
-Given a sorted integer array without duplicates, return the summary of its ranges.
+给定一个 *无重复元素* 的 *有序* 整数数组 `nums` 。
 
-*Example 1:*
+返回 _**恰好覆盖数组中所有数字** 的 *最小有序* 区间范围列表_。也就是说，`nums` 的每个元素都恰好被某个区间范围所覆盖，并且不存在属于某个范围但不属于 `nums` 的数字 `x` 。
 
-[subs="verbatim,quotes,macros"]
-----
-*Input:*  [0,1,2,4,5,7]
-*Output:* ["0->2","4->5","7"]
-*Explanation:* 0,1,2 form a continuous range; 4,5 form a continuous range.
-----
+列表中的每个区间范围 `[a,b]` 应该按如下格式输出：
 
-*Example 2:*
+* `+a->b+` ，如果 `+a != b+`
+* `a` ，如果 `a == b`
 
-[subs="verbatim,quotes,macros"]
-----
-*Input:*  [0,2,3,4,6,8,9]
-*Output:* ["0","2->4","6","8->9"]
-*Explanation:* 2,3,4 form a continuous range; 8,9 form a continuous range.
-----
+*示例 1：*
+
+....
+输入：nums = [0,1,2,4,5,7]
+输出：["0->2","4->5","7"]
+解释：区间范围是：
+[0,2] --> "0->2"
+[4,5] --> "4->5"
+[7,7] --> "7"
+....
+
+*示例 2：*
+
+....
+输入：nums = [0,2,3,4,6,8,9]
+输出：["0","2->4","6","8->9"]
+解释：区间范围是：
+[0,0] --> "0"
+[2,4] --> "2->4"
+[6,6] --> "6"
+[8,9] --> "8->9"
+....
 
+*提示：*
 
+* `+0 <= nums.length <= 20+`
+* `-2^31^ \<= nums[i] \<= 2^31^ - 1`
+* `nums` 中的所有值都 *互不相同*
+* `nums` 按升序排列
+
+
+== 思路分析
+
+双指针：如果当前元素与下一个元素相差 `1`，则继续向右推进，否则要么单独加入结果集，要么和起始节点的数字组成区间加入结果集。
 
 [[src-0228]]
+[tabs]
+====
+一刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0228_SummaryRanges.java[tag=answer]
 ----
+--
+
+// 二刷::
+// +
+// --
+// [{java_src_attr}]
+// ----
+// include::{sourcedir}/_0228_SummaryRanges_2.java[tag=answer]
+// ----
+// --
+====
+
+
+== 参考资料
 
+. https://leetcode.cn/problems/summary-ranges/solutions/553645/hui-zong-qu-jian-by-leetcode-solution-6zrs/[228. 汇总区间 - 官方题解^]
+. https://leetcode.cn/problems/summary-ranges/solutions/2411792/python3javacgotypescript-yi-ti-yi-jie-sh-gpep/[228. 汇总区间 - 一题一解：双指针（清晰题解）^]
+.  https://leetcode.cn/problems/summary-ranges/solutions/554334/shun-xu-dao-xu-hua-chuang-dan-bian-liang-gl8j/[228. 汇总区间 - 顺序 + 倒序 + 滑窗 + 单变量（4解法，超98%）^]

docs/index.adoc

@@ -539,7 +539,7 @@ include::0226-invert-binary-tree.adoc[leveloffset=+1]
 
 include::0227-basic-calculator-ii.adoc[leveloffset=+1]
 
-// include::0228-summary-ranges.adoc[leveloffset=+1]
+include::0228-summary-ranges.adoc[leveloffset=+1]
 
 // include::0229-majority-element-ii.adoc[leveloffset=+1]
 

logbook/202503.adoc

@@ -973,6 +973,10 @@ endif::[]
 |{doc_base_url}/0219-contains-duplicate-ii.adoc[题解]
 |✅ 使用哈希存每个数字的最后坐标，遇到相同就判断是否满足条件，否则继续推进。看题解，只保存滑动窗口范围内的数字，可以更节省内存！
 
+|{counter:codes2503}
+|{leetcode_base_url}/summary-ranges/[228. 汇总区间^]
+|{doc_base_url}/0228-summary-ranges.adoc[题解]
+|✅ 双指针：一个指针记录起始位置，一个指针向前推进，有起始则区间加入，没有则单独加入。
 
 |===
 

src/main/java/com/diguage/algo/leetcode/_0227_BasicCalculatorIi.java

@@ -48,6 +48,9 @@ public class _0227_BasicCalculatorIi {
      * Memory Usage: 42.8 MB, less than 5.97% of Java online submissions for Basic Calculator II.
      *
      * Copy from: https://leetcode.com/problems/basic-calculator-ii/discuss/62996/Java-straight-forward-iteration-Solution-with-comments-No-Stack-O(N)-and-O(1)[Java straight forward iteration Solution with comments, No Stack, O(N) & O(1) - LeetCode Discuss]
+     *
+     * @author D瓜哥 · https://www.diguage.com
+     * @since 2020-01-19 23:30
      */
     public int calculate(String s) {
         if (Objects.isNull(s) || s.length() == 0) {

src/main/java/com/diguage/algo/leetcode/_0228_SummaryRanges.java

@@ -0,0 +1,35 @@
+package com.diguage.algo.leetcode;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class _0228_SummaryRanges {
+  // tag::answer[]
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2025-06-14 21:50:13
+   */
+  public List<String> summaryRanges(int[] nums) {
+    List<String> result = new ArrayList<>();
+    int start = -1;
+    for (int i = 0; i < nums.length; i++) {
+      if (i < nums.length - 1 && nums[i] + 1 == nums[i + 1]) {
+        if (start == -1) {
+          start = i;
+        }
+      } else {
+        if (start == -1) {
+          result.add(String.valueOf(nums[i]));
+        } else {
+          result.add(nums[start] + "->" + nums[i]);
+          start = -1;
+        }
+      }
+    }
+    return result;
+  }
+  // end::answer[]
+  public static void main(String[] args) {
+    new _0228_SummaryRanges().summaryRanges(new int[]{0, 2, 3, 4, 6, 8, 9});
+  }
+}