From 6c0d4365c6ed1e9a47c5f31e14d59912648f4afa Mon Sep 17 00:00:00 2001
From: lizhendong128 <lizhendong128@126.com>
Date: Fri, 13 May 2022 17:26:03 +0800
Subject: [PATCH 1/2] =?UTF-8?q?=E4=BF=AE=E6=94=B90059=E8=9E=BA=E6=97=8B?=
 =?UTF-8?q?=E7=9F=A9=E9=98=B5II=20Java=E7=89=88=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

精简Java代码中不必要的变量，调整结构，减少代码量，使代码更加易读
---
 problems/0059.螺旋矩阵II.md | 44 +++++++++------------------------
 1 file changed, 12 insertions(+), 32 deletions(-)

diff --git a/problems/0059.螺旋矩阵II.md b/problems/0059.螺旋矩阵II.md
index 93735895..7afc1575 100644
--- a/problems/0059.螺旋矩阵II.md
+++ b/problems/0059.螺旋矩阵II.md
@@ -130,57 +130,37 @@ Java：
 ```Java
 class Solution {
     public int[][] generateMatrix(int n) {
+        int loop = 0;  // 控制循环次数
         int[][] res = new int[n][n];
+        int start = 0;  // 每次循环的开始点(start, start)
+        int count = 1;  // 定义填充数字
+        int i, j;
 
-        // 循环次数
-        int loop = n / 2;
-
-        // 定义每次循环起始位置
-        int startX = 0;
-        int startY = 0;
-
-        // 定义偏移量
-        int offset = 1;
-
-        // 定义填充数字
-        int count = 1;
-
-        // 定义中间位置
-        int mid = n / 2;
-        while (loop > 0) {
-            int i = startX;
-            int j = startY;
-
+        while (loop++ < n / 2) { // 判断边界后，loop从1开始
             // 模拟上侧从左到右
-            for (; j<startY + n -offset; ++j) {
-                res[startX][j] = count++;
+            for (j = start; j < n - loop; j++) {
+                res[start][j] = count++;
             }
 
             // 模拟右侧从上到下
-            for (; i<startX + n -offset; ++i) {
+            for (i = start; i < n - loop; i++) {
                 res[i][j] = count++;
             }
 
             // 模拟下侧从右到左
-            for (; j > startY; j--) {
+            for (; j >= loop; j--) {
                 res[i][j] = count++;
             }
 
             // 模拟左侧从下到上
-            for (; i > startX; i--) {
+            for (; i >= loop; i--) {
                 res[i][j] = count++;
             }
-
-            loop--;
-
-            startX += 1;
-            startY += 1;
-
-            offset += 2;
+            start++;
         }
 
         if (n % 2 == 1) {
-            res[mid][mid] = count;
+            res[start][start] = count;
         }
 
         return res;

From 0b88af0824b696be6d2f107adde3758f1df1c3f8 Mon Sep 17 00:00:00 2001
From: lizhendong128 <lizhendong128@126.com>
Date: Thu, 19 May 2022 11:08:59 +0800
Subject: [PATCH 2/2] =?UTF-8?q?=E4=BF=AE=E6=94=B90150=E9=80=86=E6=B3=A2?=
 =?UTF-8?q?=E5=85=B0=E8=A1=A8=E8=BE=BE=E5=BC=8F=E6=B1=82=E5=80=BC=20Java?=
 =?UTF-8?q?=E7=89=88=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

将for循环改为for each，使代码更加简洁。因为循环除了对token进行遍历，i并没有其他用途。
---
 problems/0150.逆波兰表达式求值.md | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/problems/0150.逆波兰表达式求值.md b/problems/0150.逆波兰表达式求值.md
index fd3d69aa..6ce7e2f9 100644
--- a/problems/0150.逆波兰表达式求值.md
+++ b/problems/0150.逆波兰表达式求值.md
@@ -136,19 +136,19 @@ java:
 class Solution {
     public int evalRPN(String[] tokens) {
         Deque<Integer> stack = new LinkedList();
-        for (int i = 0; i < tokens.length; ++i) {
-            if ("+".equals(tokens[i])) {        // leetcode 内置jdk的问题，不能使用==判断字符串是否相等
+        for (String s : tokens) {
+            if ("+".equals(s)) {        // leetcode 内置jdk的问题，不能使用==判断字符串是否相等
                 stack.push(stack.pop() + stack.pop());      // 注意 - 和/ 需要特殊处理
-            } else if ("-".equals(tokens[i])) {
+            } else if ("-".equals(s)) {
                 stack.push(-stack.pop() + stack.pop());
-            } else if ("*".equals(tokens[i])) {
+            } else if ("*".equals(s)) {
                 stack.push(stack.pop() * stack.pop());
-            } else if ("/".equals(tokens[i])) {
+            } else if ("/".equals(s)) {
                 int temp1 = stack.pop();
                 int temp2 = stack.pop();
                 stack.push(temp2 / temp1);
             } else {
-                stack.push(Integer.valueOf(tokens[i]));
+                stack.push(Integer.valueOf(s));
             }
         }
         return stack.pop();