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+# [344. Reverse String](https://leetcode.com/problems/reverse-string/description/)
+# 思路
+翻转字符串。   
+注意：交换元素时，最好用标准库里的swap，快一些。
+# C++
+```
+class Solution {
+public:
+    string reverseString(string s) {
+        int low = 0, high = s.size() - 1;
+        while(low < high){
+            swap(s[low++], s[high--]); // 库里的swap比自己写的要快一些
+        }
+        return s;
+        
+    }
+};
+```