Update solution 059 [Java]

Author: yanglbme

README.md

@@ -62,6 +62,7 @@ Complete [solutions](https://github.com/doocs/leetcode/tree/master/solution) to
 | 046 | [Permutations](https://github.com/doocs/leetcode/tree/master/solution/046.Permutations) | `Backtracking` |
 | 047 | [Permutations II](https://github.com/doocs/leetcode/tree/master/solution/047.Permutations%20II) | `Backtracking` |
 | 054 | [Spiral Matrix](https://github.com/doocs/leetcode/tree/master/solution/054.Spiral%20Matrix) | `Array` |
+| 059 | [Spiral Matrix II](https://github.com/doocs/leetcode/tree/master/solution/059.Spiral%20Matrix%20II) | `Array` |
 | 061 | [Rotate List](https://github.com/doocs/leetcode/tree/master/solution/061.Rotate%20List) | `Linked List`, `Two Pointers` |
 | 062 | [Unique Paths](https://github.com/doocs/leetcode/tree/master/solution/062.Unique%20Paths) | `Array`, `Dynamic Programming` |
 | 063 | [Unique Paths II](https://github.com/doocs/leetcode/tree/master/solution/063.Unique%20Paths%20II) | `Array`, `Dynamic Programming` |
@@ -104,8 +105,8 @@ I'm looking for long-term contributors/partners to this repo! Send me [PRs](http
 " If you want to go fast, go alone. If you want to go far, go together. And that's the spirit of [teamwork](https://github.com/doocs/leetcode/graphs/contributors) ".
 
 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
-| <center> [<img src="https://avatars3.githubusercontent.com/u/21008209?v=4" width="80px;"/>](https://github.com/yanglbme)<br />[💻](https://github.com/doocs/leetcode/commits?author=yanglbme "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/23625436?v=4" width="80px;"/>](https://github.com/chakyam)<br />[💻](https://github.com/doocs/leetcode/commits?author=chakyam "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/10081554?v=4" width="80px;"/>](https://github.com/zhkmxx9302013)<br />[💻](https://github.com/doocs/leetcode/commits?author=zhkmxx9302013 "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/40383345?v=4" width="80px;"/>](https://github.com/MarkKuang1991)<br />[💻](https://github.com/doocs/leetcode/commits?author=MarkKuang1991 "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/12371194?v=4" width="80px;"/>](https://github.com/fonxian)<br />[💻](https://github.com/doocs/leetcode/commits?author=fonxian "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/25222367?v=4" width="80px;"/>](https://github.com/zhanary)<br />[💻](https://github.com/doocs/leetcode/commits?author=zhanary "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/42396616?v=4" width="80px;"/>](https://github.com/ZhouTingZhaobiu)<br />[💻](https://github.com/doocs/leetcode/commits?author=ZhouTingZhaobiu "Code") </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/31923541?v=4" width="80px;"/>](https://github.com/zouwx2cs)<br />[💻](https://github.com/doocs/leetcode/commits?author=zouwx2cs "Code") </center> |
+| <center> [<img src="https://avatars3.githubusercontent.com/u/21008209?v=4" width="80px;"/>](https://github.com/yanglbme) </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/23625436?v=4" width="80px;"/>](https://github.com/chakyam) </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/10081554?v=4" width="80px;"/>](https://github.com/zhkmxx9302013) </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/40383345?v=4" width="80px;"/>](https://github.com/MarkKuang1991) </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/12371194?v=4" width="80px;"/>](https://github.com/fonxian) </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/25222367?v=4" width="80px;"/>](https://github.com/zhanary) </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/42396616?v=4" width="80px;"/>](https://github.com/ZhouTingZhaobiu) </center> | <center> [<img src="https://avatars3.githubusercontent.com/u/31923541?v=4" width="80px;"/>](https://github.com/zouwx2cs) </center> |
 |---|---|---|---|---|---|---|---|
-| <center> [<img src="https://avatars3.githubusercontent.com/u/20679510?v=4" width="80px;"/>](https://github.com/Mrzhudky)<br />[💻](https://github.com/doocs/leetcode/commits?author=Mrzhudky "Code") </center> | 
+| <center> [<img src="https://avatars3.githubusercontent.com/u/20679510?v=4" width="80px;"/>](https://github.com/Mrzhudky) </center> |
 
 <!-- ALL-CONTRIBUTORS-LIST:END -->

solution/059.Spiral Matrix II/README.md

@@ -0,0 +1,56 @@
+## 螺旋矩阵 II
+### 题目描述
+
+给定一个正整数 n，生成一个包含 1 到 n² 所有元素，且元素按顺时针顺序螺旋排列的正方形矩阵。
+
+**示例:**
+```
+输入: 3
+输出:
+[
+ [ 1, 2, 3 ],
+ [ 8, 9, 4 ],
+ [ 7, 6, 5 ]
+]
+```
+
+### 解法
+定义一个变量 `val`，由外往里，一圈圈遍历矩阵，进行赋值，每次赋值后 `val++`。
+
+
+```java
+class Solution {
+    public int[][] generateMatrix(int n) {
+        if (n < 1) {
+            return null;
+        }
+        
+        int[][] res = new int[n][n];
+        int val = 1;
+        
+        int m1 = 0;
+        int m2 = n - 1;
+        while (m1 < m2) {
+            for (int j = m1; j < m2; ++j) {
+                res[m1][j] = val++;
+            }
+            for (int i = m1; i < m2; ++i) {
+                res[i][m2] = val++;
+            }
+            for (int j = m2; j > m1; --j) {
+                res[m2][j] = val++;
+            }
+            for (int i = m2; i > m1; --i) {
+                res[i][m1] = val++;
+            }
+            ++m1;
+            --m2;
+        }
+        if (m1 == m2) {
+            res[m1][m1] = val;
+        }
+        
+        return res;
+    }
+}
+```

solution/059.Spiral Matrix II/Solution.java

@@ -0,0 +1,34 @@
+class Solution {
+    public int[][] generateMatrix(int n) {
+        if (n < 1) {
+            return null;
+        }
+        
+        int[][] res = new int[n][n];
+        int val = 1;
+        
+        int m1 = 0;
+        int m2 = n - 1;
+        while (m1 < m2) {
+            for (int j = m1; j < m2; ++j) {
+                res[m1][j] = val++;
+            }
+            for (int i = m1; i < m2; ++i) {
+                res[i][m2] = val++;
+            }
+            for (int j = m2; j > m1; --j) {
+                res[m2][j] = val++;
+            }
+            for (int i = m2; i > m1; --i) {
+                res[i][m1] = val++;
+            }
+            ++m1;
+            --m2;
+        }
+        if (m1 == m2) {
+            res[m1][m1] = val;
+        }
+        
+        return res;
+    }
+}