add 412. Fizz Buzz 🍺

README.md

@@ -278,6 +278,7 @@ My LeetCode solutions with Chinese explanation. 我的LeetCode中文题解。
 | 404 |[Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/404.%20Sum%20of%20Left%20Leaves.md)|Easy|  |
 | 405 |[Convert a Number to Hexadecimal](https://leetcode.com/problems/convert-a-number-to-hexadecimal)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/405.%20Convert%20a%20Number%20to%20Hexadecimal.md)|Easy|  |
 | 409 |[Longest Palindrome](https://leetcode.com/problems/longest-palindrome)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/409.%20Longest%20Palindrome.md)|Easy|  |
+| 412 |[Fizz Buzz](https://leetcode.com/problems/fizz-buzz/)|[C++](solutions/412.%20Fizz%20Buzz.md)|Easy|  |
 | 414 |[Third Maximum Number](https://leetcode.com/problems/third-maximum-number)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/414.%20Third%20Maximum%20Number.md)|Easy|  |
 | 415 |[Add Strings](https://leetcode.com/problems/add-strings)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/415.%20Add%20Strings.md)|Easy|  |
 | 416 |[Partition Equal Subset Sum](https://leetcode.com/problems/partition-equal-subset-sum/)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/416.%20Partition%20Equal%20Subset%20Sum.md)|Medium|  |

solutions/412. Fizz Buzz.md

@@ -0,0 +1,51 @@
+# [412. Fizz Buzz](https://leetcode.com/problems/fizz-buzz/)
+
+# 思路
+
+这题很简单，我们可以用for循环从i=1到i=n，然后判断i是否是3或者5的倍数。
+
+评论区说因为取余操作`%`比较费时，所以我们应该避免取余，下面代码给出了两种避免取余的思路，亲测确实比直接取余要快一点点。
+
+# C++
+``` C++
+class Solution {
+public:
+    vector<string> fizzBuzz(int n) {
+        vector<string>res(n);
+        for(int i = 1; i <= n; i++) res[i-1] = to_string(i);
+        for(int i = 2; i < n; i+=3) res[i] = "Fizz";
+        for(int i = 4; i < n; i+=5) res[i] = "Buzz";
+        for(int i = 14; i < n; i+=15) res[i] = "FizzBuzz";
+
+        return res;
+    }
+};
+```
+
+``` C++
+class Solution {
+public:
+    vector<string> fizzBuzz(int n) {
+        vector<string>res(n);
+        
+        int fizz = 3, buzz = 5;
+        for(int i = 1; i <= n; i++){
+            if(i == fizz){
+                res[i-1] = "Fizz";
+                fizz += 3;
+                if(i == buzz){
+                    buzz += 5;
+                    res[i-1] += "Buzz";
+                }
+            }
+            else if(i == buzz){
+                    buzz += 5;
+                    res[i-1] = "Buzz";
+            }
+            else res[i-1] = to_string(i);
+        }
+
+        return res;
+    }
+};
+```