solve problem Add Binary

Author: P-ppc

README.md

@@ -128,6 +128,7 @@ All solutions will be accepted!
 |747|[Largest Number At Least Twice Of Others](https://leetcode-cn.com/problems/largest-number-at-least-twice-of-others/description/)|[java/py/js](./algorithms/LargestNumberAtLeastTwiceOfOthers)|Easy|
 |455|[assign cookies](https://leetcode-cn.com/problems/assign-cookies/description/)|[java/py/js](./algorithms/AssignCookies)|Easy|
 |415|[Add Strings](https://leetcode-cn.com/problems/add-strings/description/)|[java/py/js](./algorithms/AddStrings)|Easy|
+|67|[Add Binary](https://leetcode-cn.com/problems/add-binary/description/)|[java/py/js](./algorithms/AddBinary)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/AddBinary/README.md

@@ -0,0 +1,2 @@
+# Add Binary
+This problem is easy to solve, like problem Add Strings

algorithms/AddBinary/Solution.java

@@ -0,0 +1,21 @@
+class Solution {
+    public String addBinary(String a, String b) {
+        String res = "";
+        int carry = 0,
+            i = a.length() - 1,
+            j = b.length() - 1;
+        
+        while (i >= 0 || j >= 0) {
+            int x = i >= 0 ? a.charAt(i) - '0' : 0,
+                y = j >= 0 ? b.charAt(j) - '0' : 0,
+                sum = x + y + carry;
+            
+            res = String.valueOf(sum % 2) + res;
+            carry = sum / 2;
+            i--;
+            j--;
+        }
+        
+        return carry == 1 ? "1" + res : res;
+    }
+}

algorithms/AddBinary/solution.js

@@ -0,0 +1,24 @@
+/**
+ * @param {string} a
+ * @param {string} b
+ * @return {string}
+ */
+var addBinary = function(a, b) {
+    let res = '',
+        carry = 0,
+        i = a.length - 1,
+        j = b.length - 1
+    
+    while (i >= 0 || j >= 0) {
+        let x = i >= 0 ? a[i] - '0' : 0,
+            y = j >= 0 ? b[j] - '0' : 0,
+            sum = x + y + carry
+        
+        res = String(sum % 2) + res
+        carry = parseInt(sum / 2)
+        i--
+        j--
+    }
+    
+    return carry ? '1' + res : res
+};

algorithms/AddBinary/solution.py

@@ -0,0 +1,22 @@
+class Solution(object):
+    def addBinary(self, a, b):
+        """
+        :type a: str
+        :type b: str
+        :rtype: str
+        """
+        res = ''
+        carry = 0
+        i = len(a) - 1
+        j = len(b) - 1
+        
+        while i >= 0 or j >= 0:
+            x = ord(a[i]) - ord('0') if i >= 0 else 0
+            y = ord(b[j]) - ord('0') if j >= 0 else 0
+            sm = x + y + carry
+            res = str(sm % 2) + res
+            carry = sm / 2
+            i -= 1
+            j -= 1
+            
+        return '1' + res if carry == 1 else res