add 067

Author: Blankj

note/067/README.md

@@ -0,0 +1,56 @@
+# [Plus One][title]
+
+## Description
+
+Given two binary strings, return their sum (also a binary string).
+
+For example,
+a = `"11"`
+b = `"1"`
+Return `"100"`.
+
+**Tags:** Math, String
+
+
+## 思路
+
+题意是给你两个二进制串，求其和的二进制串。
+
+``` java
+public class Solution {
+    public String addBinary(String a, String b) {
+        StringBuilder sb = new StringBuilder();
+        int carry = 0, p1 = a.length() - 1, p2 = b.length() - 1;
+        while (p1 >= 0 && p2 >= 0) {
+            carry += p1 >= 0 ? a.charAt(p1--) - '0' : 0;
+            carry += p2 >= 0 ? b.charAt(p2--) - '0' : 0;
+            sb.insert(0, (char) (carry % 2 + '0'));
+            carry >>= 1;
+        }
+        while (p1 >= 0) {
+            carry += p1 >= 0 ? a.charAt(p1--) - '0' : 0;
+            sb.insert(0, (char) (carry % 2 + '0'));
+            carry >>= 1;
+        }
+        while (p2 >= 0) {
+            carry += p2 >= 0 ? b.charAt(p2--) - '0' : 0;
+            sb.insert(0, (char) (carry % 2 + '0'));
+            carry >>= 1;
+        }
+        if (carry == 1) {
+            sb.insert(0, '1');
+        }
+        return sb.toString();
+    }
+}
+```
+
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我GitHub上的LeetCode题解：[awesome-java-leetcode][ajl]
+
+
+
+[title]: https://leetcode.com/problems/plus-one
+[ajl]: https://github.com/Blankj/awesome-java-leetcode

project/LeetCode/leetcode/src/main/java/com/blankj/easy/_066/Solution.java

@@ -1,7 +1,5 @@
 package com.blankj.easy._066;
 
-import java.io.File;
-
 /**
  * <pre>
  *     author: Blankj

project/LeetCode/leetcode/src/main/java/com/blankj/easy/_067/Solution.java

@@ -0,0 +1,54 @@
+package com.blankj.easy._067;
+
+/**
+ * <pre>
+ *     author: Blankj
+ *     blog  : http://blankj.com
+ *     time  : 2017/04/21
+ *     desc  :
+ * </pre>
+ */
+
+public class Solution {
+    public String addBinary(String a, String b) {
+        StringBuilder sb = new StringBuilder();
+        int carry = 0, p1 = a.length() - 1, p2 = b.length() - 1;
+        while (p1 >= 0 && p2 >= 0) {
+            carry += a.charAt(p1--);
+            carry += b.charAt(p2--);
+            sb.insert(0, (char) (carry % 2 + '0'));
+            carry >>= 1;
+        }
+        while (p1 >= 0) {
+            carry += a.charAt(p1--) - '0';
+            sb.insert(0, (char) (carry % 2 + '0'));
+            carry >>= 1;
+        }
+        while (p2 >= 0) {
+            carry += b.charAt(p2--) - '0';
+            sb.insert(0, (char) (carry % 2 + '0'));
+            carry >>= 1;
+        }
+        if (carry == 1) {
+            sb.insert(0, '1');
+        }
+        return sb.toString();
+    }
+
+//    public String addBinary(String a, String b) {
+//        StringBuilder sb = new StringBuilder();
+//        int carry = 0, p1 = a.length() - 1, p2 = b.length() - 1;
+//        while (p1 >= 0 || p2 >= 0 || carry == 1) {
+//            carry += p1 >= 0 ? a.charAt(p1--) - '0' : 0;
+//            carry += p2 >= 0 ? b.charAt(p2--) - '0' : 0;
+//            sb.insert(0, (char) (carry % 2 + '0'));
+//            carry >>= 1;
+//        }
+//        return sb.toString();
+//    }
+
+    public static void main(String[] args) {
+        Solution solution = new Solution();
+        System.out.println(solution.addBinary("11", "1"));
+    }
+}