Update 29. 顺时针打印矩阵.md

题目链接改为力扣中的对应题目，题目描述和代码按该题的接口调整。

notes/29. 顺时针打印矩阵.md

@@ -2,7 +2,7 @@
 
 ## 题目链接
 
-[牛客网](https://www.nowcoder.com/practice/9b4c81a02cd34f76be2659fa0d54342a?tpId=13&tqId=11172&tPage=1&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking&from=cyc_github)
+[Leetcode](https://leetcode.cn/problems/shun-shi-zhen-da-yin-ju-zhen-lcof/)
 
 ## 题目描述
 
@@ -19,25 +19,39 @@
 <div align="center"> <img src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/image-20201104010609223.png" width="500px"> </div><br>
 
 ```java
-public ArrayList<Integer> printMatrix(int[][] matrix) {
-    ArrayList<Integer> ret = new ArrayList<>();
-    int r1 = 0, r2 = matrix.length - 1, c1 = 0, c2 = matrix[0].length - 1;
+public int[] spiralArray(int[][] array) {
+    if (array == null || array.length == 0 || array[0].length == 0) {
+        return new int[0];
+    }
+    int m = array.length, n = array[0].length;
+    int[] ret = new int[m * n];
+    int idx = 0;
+    int r1 = 0, r2 = m - 1, c1 = 0, c2 = n - 1;
     while (r1 <= r2 && c1 <= c2) {
         // 上
-        for (int i = c1; i <= c2; i++)
-            ret.add(matrix[r1][i]);
+        for (int i = c1; i <= c2; i++) {
+            ret[idx++] = array[r1][i];
+        }
         // 右
-        for (int i = r1 + 1; i <= r2; i++)
-            ret.add(matrix[i][c2]);
-        if (r1 != r2)
+        for (int i = r1 + 1; i <= r2; i++) {
+            ret[idx++] = array[i][c2];
+        }
+        if (r1 != r2) {
             // 下
-            for (int i = c2 - 1; i >= c1; i--)
-                ret.add(matrix[r2][i]);
-        if (c1 != c2)
+            for (int i = c2 - 1; i >= c1; i--) {
+                ret[idx++] = array[r2][i];
+            }
+        }
+        if (c1 != c2) {
             // 左
-            for (int i = r2 - 1; i > r1; i--)
-                ret.add(matrix[i][c1]);
-        r1++; r2--; c1++; c2--;
+            for (int i = r2 - 1; i > r1; i--) {
+                ret[idx++] = array[i][c1];
+            }
+        }
+        r1++;
+        r2--;
+        c1++;
+        c2--;
     }
     return ret;
 }