add 168 solution

Author: feiyutalk

problems/168. Excel Sheet Column Title/README.md

@@ -0,0 +1,22 @@
+# 168. Excel Sheet Column Title
+
+## #1 除于取余[AC]
+
+### 算法
+
+```java
+class Solution {
+    public String convertToTitle(int n) {
+        StringBuilder result = new StringBuilder();
+
+        while(n>0){
+            n--;
+            result.insert(0, (char)('A' + n % 26));
+            n /= 26;
+        }
+
+        return result.toString();
+    }
+}
+```
+