**Solution**

**Find the Difference** https://leetcode.com/problems/find-the-difference/

**Use 2 counters to find the missing character**

```
from collections import Counter
class Solution(object):
def findTheDifference(self, s, t):
"""
:type s: str
:type t: str
:rtype: str
"""
sc, tc = Counter(s), Counter(t)
for x in tc:
if x not in sc or sc[x] != tc[x]:
return x
return
```

**Use XOR in an intelligent Manner**

```
class Solution(object):
def findTheDifference(self, s, t):
"""
:type s: str
:type t: str
:rtype: str
"""
xor_sum = 0
for x in s:
xor_sum = xor_sum ^ ord(x)
for y in t:
xor_sum = xor_sum ^ ord(y)
return chr(xor_sum)
```