二刷48

docs/0048-rotate-image.adoc

@@ -13,6 +13,8 @@ You have to rotate the image https://en.wikipedia.org/wiki/In-place_algorithm[*i
 
 *Example 1:*
 
+image::images/0048-00.jpg[{image_attr}]
+
 [subs="verbatim,quotes,macros"]
 ----
 Given *input matrix* = 
@@ -32,6 +34,8 @@ rotate the input matrix *in-place* such that it becomes:
 
 *Example 2:*
 
+image::images/0048-01.jpg[{image_attr}]
+
 [subs="verbatim,quotes,macros"]
 ----
 Given *input matrix* =
@@ -51,10 +55,47 @@ rotate the input matrix *in-place* such that it becomes:
 ]
 ----
 
+== 思路分析
+
+将矩阵周围一圈，划分成四个区域。如下图所示：
+
+image::images/0048-02.png[{image_attr}]
+
+这样每个区域长度相等，使用循环做数字交换即可。另外，借助回溯思想，利用递归推进层次。
+
+image:images/0048-03.png[{image_attr}]
+
+image:images/0048-04.png[{image_attr}]
+
+下面辅助矩阵的方案也不错：
+
+image:images/0048-05.png[{image_attr}]
+
+官方题解中的翻转矩阵的方案也不错！
 
 [[src-0048]]
+[tabs]
+====
+一刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0048_RotateImage.java[tag=answer]
 ----
+--
+
+二刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0048_RotateImage_2.java[tag=answer]
+----
+--
+====
+
+== 参考资料
 
+. https://leetcode.cn/problems/rotate-image/solutions/1228078/48-xuan-zhuan-tu-xiang-fu-zhu-ju-zhen-yu-jobi/?envType=study-plan-v2&envId=selected-coding-interview[48. 旋转图像 - 辅助矩阵 / 原地修改，清晰图解^]
+. https://leetcode.cn/problems/rotate-image/solutions/526980/xuan-zhuan-tu-xiang-by-leetcode-solution-vu3m/?envType=study-plan-v2&envId=selected-coding-interview[48. 旋转图像 - 官方题解^]

logbook/202406.adoc

@@ -747,6 +747,11 @@
 |{doc_base_url}/0151-reverse-words-in-a-string.adoc[题解]
 |✅ 更优解是倒序遍历数组，用双指针记录单词下标。
 
+|{counter:codes}
+|{leetcode_base_url}/rotate-image/[48. Rotate Image^]
+|{doc_base_url}/0048-rotate-image.adoc[题解]
+|✅ 回溯，或翻转，或行转列
+
 |===
 
 截止目前，本轮练习一共完成 {codes} 道题。

src/main/java/com/diguage/algo/leetcode/_0048_RotateImage.java

@@ -59,11 +59,14 @@
  * @since 2019-10-24 00:57:55
  */
 public class _0048_RotateImage {
-  // tag::answer[]
+    // tag::answer[]
     /**
      * Runtime: 0 ms, faster than 100.00% of Java online submissions for Rotate Image.
      *
      * Memory Usage: 36.3 MB, less than 100.00% of Java online submissions for Rotate Image.
+     *
+     * @author D瓜哥 · https://www.diguage.com
+     * @since 2019-10-24 00:57:55
      */
     public void rotate(int[][] matrix) {
         if (Objects.isNull(matrix) || matrix.length == 0) {

src/main/java/com/diguage/algo/leetcode/_0048_RotateImage_2.java

@@ -0,0 +1,32 @@
+package com.diguage.algo.leetcode;
+
+public class _0048_RotateImage_2 {
+  // tag::answer[]
+
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2024-09-19 17:35:53
+   */
+  public void rotate(int[][] matrix) {
+    backtrack(matrix, 0, 0,
+      matrix.length, matrix.length);
+  }
+
+  private void backtrack(int[][] matrix,
+                         int row, int column,
+                         int rLen, int cLen) {
+    if (rLen <= 1) {
+      return;
+    }
+    // 旋转
+    for (int i = 0; i < cLen - 1; i++) {
+      int tmp = matrix[row][column + i];
+      matrix[row][column + i] = matrix[row + rLen - 1 - i][column];
+      matrix[row + rLen - 1 - i][column] = matrix[row + rLen - 1][column + cLen - 1 - i];
+      matrix[row + rLen - 1][column + cLen - 1 - i] = matrix[row + i][column + cLen - 1];
+      matrix[row + i][column + cLen - 1] = tmp;
+    }
+    backtrack(matrix, row + 1, column + 1, rLen - 2, cLen - 2);
+  }
+  // end::answer[]
+}