add 171 solution

feiyutalk · feiyutalk · commit 559899ef28c0 · 2018-04-21T23:14:39.000+08:00
diff --git a/problems/171. Excel Sheet Column Number/README.md b/problems/171. Excel Sheet Column Number/README.md
@@ -0,0 +1,22 @@
+# 171. Excel Sheet Column Number
+
+## #1 乘膜累加[AC]
+
+### 算法
+
+```java
+class Solution {
+    public int titleToNumber(String s) {
+        if(s == null || s.length() == 0)
+            return 0;
+        int power = 1;
+        int res = 0;
+        for(int i=s.length()-1; i>=0; i--){
+            res += ((s.charAt(i) - 'A' + 1)*power);
+            power *= 26;
+        }
+        return res;
+    }
+}
+```
+
