diff --git a/README.md b/README.md
index 24009809..a8c88c9b 100644
--- a/README.md
+++ b/README.md
@@ -9,13 +9,13 @@ LeetCode 最强题解（持续更新中）:
|[0018.四数之和](https://github.com/youngyangyang04/leetcode/blob/master/problems/0018.四数之和) | 数组 |中等|**双指针**|
|[0021.合并两个有序链表](https://github.com/youngyangyang04/leetcode/blob/master/problems/0021.合并两个有序链表.md) |链表 |简单|**模拟** |
|[0026.删除排序数组中的重复项](https://github.com/youngyangyang04/leetcode/blob/master/problems/0026.删除排序数组中的重复项.md) |数组 |简单|**暴力** **快慢指针** |
-|[0027.移除元素](https://github.com/youngyangyang04/leetcode/blob/master/problems/0027.移除元素.md) |数组 |简单| **暴力** **快慢指针**|
+|[0027.移除元素](https://github.com/youngyangyang04/leetcode/blob/master/problems/0027.移除元素.md) |数组 |简单| **暴力** **快慢指针/双指针**|
|[0028.实现strStr()](https://github.com/youngyangyang04/leetcode/blob/master/problems/0028.实现strStr().md) |字符串 |简单| **KMP** |
|[0035.搜索插入位置](https://github.com/youngyangyang04/leetcode/blob/master/problems/0035.搜索插入位置.md) |数组 |简单| **暴力** **二分**|
|[0053.最大子序和](https://github.com/youngyangyang04/leetcode/blob/master/problems/0053.最大子序和.md) |数组 |简单|**暴力** **贪心** 动态规划 分治|
|[0059.螺旋矩阵II](https://github.com/youngyangyang04/leetcode/blob/master/problems/0059.螺旋矩阵II.md) |数组 |中等|**模拟**|
|[0083.删除排序链表中的重复元素](https://github.com/youngyangyang04/leetcode/blob/master/problems/0083.删除排序链表中的重复元素.md) |链表 |简单|**模拟**|
-|[0142.环形链表II](https://github.com/youngyangyang04/leetcode/blob/master/problems/0142.环形链表II.md) |链表 |中等|**模拟**|
+|[0142.环形链表II](https://github.com/youngyangyang04/leetcode/blob/master/problems/0142.环形链表II.md) |链表 |中等|**快慢指针/双指针**|
|[0151.翻转字符串里的单词](https://github.com/youngyangyang04/leetcode/blob/master/problems/0151.翻转字符串里的单词.md) |字符串 |中等|**模拟**|
|[0202.快乐数](https://github.com/youngyangyang04/leetcode/blob/master/problems/0202.快乐数.md) |哈希表 |简单|**哈希**|
|[0203.移除链表元素](https://github.com/youngyangyang04/leetcode/blob/master/problems/0203.移除链表元素.md) |链表 |简单|**模拟** **虚拟头结点**|
@@ -34,7 +34,7 @@ LeetCode 最强题解（持续更新中）:
|[0575.分糖果.md](https://github.com/youngyangyang04/leetcode/blob/master/problems/0575.分糖果.md) |哈希表 |简单|**哈希**|
|[0705.设计哈希集合](https://github.com/youngyangyang04/leetcode/blob/master/problems/0705.设计哈希集合.md) |哈希表 |简单|**模拟**|
|[0707.设计链表](https://github.com/youngyangyang04/leetcode/blob/master/problems/0707.设计链表.md) |链表 |中等|**模拟**|
-|[剑指Offer05.替换空格](https://github.com/youngyangyang04/leetcode/blob/master/problems/剑指Offer05.替换空格.md) |字符串 |简单|**模拟**|
+|[剑指Offer05.替换空格](https://github.com/youngyangyang04/leetcode/blob/master/problems/剑指Offer05.替换空格.md) |字符串 |简单|**双指针**|
Leetcode精选：
diff --git a/pics/剑指Offer05.替换空格.png b/pics/剑指Offer05.替换空格.png
new file mode 100644
index 00000000..e4a2dfbc
Binary files /dev/null and b/pics/剑指Offer05.替换空格.png differ
diff --git a/problems/剑指Offer05.替换空格.md b/problems/剑指Offer05.替换空格.md
index 80b5301e..8a45078e 100644
--- a/problems/剑指Offer05.替换空格.md
+++ b/problems/剑指Offer05.替换空格.md
@@ -1,16 +1,22 @@
## 题目地址
https://leetcode-cn.com/problems/ti-huan-kong-ge-lcof/
-
## 思路
如果想把这道题目做到极致，就不要只用额外的辅助空间，先扩充数组到每个空格替换成"%20"之后的大小
-然后从后向前替换空格
+然后从后向前替换空格，双指针法：
+思路如下：
+
+
+时间复杂度，空间复杂度均超过100%的用户
+
+
## C++代码
-时间复杂度，空间复杂度均超过100%的用户
```
class Solution {
@@ -23,10 +29,11 @@ public:
count++;
}
}
- s.resize(s.size() + count * 2); // 扩充字符串s的大小，也就是每个空格替换成"%20"之后的大小
+ // 扩充字符串s的大小，也就是每个空格替换成"%20"之后的大小
+ s.resize(s.size() + count * 2);
int sNewSize = s.size();
// 从后先前将空格替换为"%20"
- for (int i = sNewSize - 1, j = sOldSize - 1; i >= 0, j >= 0; i--, j--) {
+ for (int i = sNewSize - 1, j = sOldSize - 1; j < i; i--, j--) {
if (s[j] != ' ') {
s[i] = s[j];
} else {
@@ -39,5 +46,6 @@ public:
return s;
}
};
+
```
> 笔者在先后在腾讯和百度从事技术研发多年，利用工作之余重刷leetcode，本文 [GitHub](https://github.com/youngyangyang04/leetcode-master )：https://github.com/youngyangyang04/leetcode-master 已经收录，欢迎star，fork，共同学习，一起进步。
diff --git a/video/替换空格.mp4 b/video/替换空格.mp4
new file mode 100644
index 00000000..223743cd
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