二刷75

Author: diguage

docs/0000-counting-sort.adoc

@@ -3,3 +3,7 @@
 
 
 image::images/counting-sort-overview.png[{image_attr}]
+
+== 经典题目
+
+. xref:0075-sort-colors.adoc[75. Sort Colors]

docs/0000-quick-sort.adoc

@@ -15,3 +15,6 @@ image::images/quick-sort-01.gif[{image_attr}]
 image::images/quick-sort-02.gif[{image_attr}]
 
 image::images/quick-sort-03.png[{image_attr}]
+
+
+NOTE: 研究一下三路快排。

docs/0075-sort-colors.adoc

@@ -1,36 +1,71 @@
 [#0075-sort-colors]
-= 75. Sort Colors
+= 75. 颜色分类
 
-{leetcode}/problems/sort-colors/[LeetCode - Sort Colors^]
+https://leetcode.cn/problems/sort-colors/[LeetCode - 75. 颜色分类^]
 
-Given an array with _n_ objects colored red, white or blue, sort them *https://en.wikipedia.org/wiki/In-place_algorithm[in-place^] *so that objects of the same color are adjacent, with the colors in the order red, white and blue.
+给定一个包含红色、白色和蓝色、共 `n` 个元素的数组 `nums`，**https://baike.baidu.com/item/%E5%8E%9F%E5%9C%B0%E7%AE%97%E6%B3%95[原地]**对它们进行排序，使得相同颜色的元素相邻，并按照红色、白色、蓝色顺序排列。
 
-Here, we will use the integers 0, 1, and 2 to represent the color red, white, and blue respectively.
+我们使用整数 `0`、 `1` 和 `2` 分别表示红色、白色和蓝色。
 
-*Note:* You are not suppose to use the library's sort function for this problem.
+必须在不使用库内置的 sort 函数的情况下解决这个问题。
 
-*Example:*
+*示例 1：*
 
-[subs="verbatim,quotes,macros"]
-----
-*Input:* [2,0,2,1,1,0]
-*Output:* [0,0,1,1,2,2]
-----
+....
+输入：nums = [2,0,2,1,1,0]
+输出：[0,0,1,1,2,2]
+....
+
+*示例 2：*
+
+....
+输入：nums = [2,0,1]
+输出：[0,1,2]
+....
+
+*提示：*
+
+* `+n == nums.length+`
+* `1 \<= n \<= 300`
+* `nums[i]` 为 `0`、`1` 或 `2`
 
-*Follow up:*
+*进阶：*
 
+* 你能想出一个仅使用常数空间的一趟扫描算法吗？
 
-* A rather straight forward solution is a two-pass algorithm using counting sort.
 
 
-	First, iterate the array counting number of 0's, 1's, and 2's, then overwrite array with total number of 0's, then 1's and followed by 2's.
-* Could you come up with a one-pass algorithm using only constant space?
+== 思路分析
 
+经典的荷兰国旗问题，最合适的解法是：“三路快排”。
 
+统计 `0`、 `1` 和 `2` 的个数。然后在数组中依次填入。
 
 [[src-0075]]
+[tabs]
+====
+一刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0075_SortColors.java[tag=answer]
 ----
+--
+
+二刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0075_SortColors_2.java[tag=answer]
+----
+--
+====
+
+
+== 参考资料
 
+. https://leetcode.cn/problems/sort-colors/solutions/437968/yan-se-fen-lei-by-leetcode-solution/[75. 颜色分类 - 官方题解^]
+. https://leetcode.cn/problems/sort-colors/solutions/3679069/on-cha-ru-pai-xu-jian-ji-xie-fa-pythonja-zk60/[75. 颜色分类 - O(n) 插入排序，简洁写法^]
+. https://leetcode.cn/problems/sort-colors/solutions/71322/kuai-su-pai-xu-partition-guo-cheng-she-ji-xun-huan/[75. 颜色分类 - 「三路快排」应用^]

logbook/202503.adoc

@@ -1934,6 +1934,11 @@ endif::[]
 |{doc_base_url}/0076-minimum-window-substring.adoc[题解]
 |✅ 滑动窗口。字母不够时，扩大窗口；字母足够时，开始缩小窗口。
 
+|{counter:codes2503}
+|{leetcode_base_url}/sort-colors/[75. Sort Colors^]
+|{doc_base_url}/0075-sort-colors.adoc[题解]
+|✅ 计数排序或三路快排。
+
 |===
 
 截止目前，本轮练习一共完成 {codes2503} 道题。

src/main/java/com/diguage/algo/leetcode/_0075_SortColors_2.java

@@ -0,0 +1,22 @@
+package com.diguage.algo.leetcode;
+
+public class _0075_SortColors_2 {
+  // tag::answer[]
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2025-11-17 21:37:31
+   */
+  public void sortColors(int[] nums) {
+    int[] counter = new int[3];
+    for (int num : nums) {
+      counter[num]++;
+    }
+    int index = 0;
+    for (int i = 0; i < counter.length; i++) {
+      for (int j = 0; j < counter[i]; j++) {
+        nums[index++] = i;
+      }
+    }
+  }
+  // end::answer[]
+}