## Solutions
### Pointer
```python
class Solution(object):
def mergeAlternately(self, word1, word2):
"""
:type word1: str
:type word2: str
:rtype: str
"""
p = 0
merged_string = []
while p < len(word1) and p < len(word2):
merged_string.append(word1[p])
merged_string.append(word2[p])
p+=1
if p < len(word1):
merged_string.append(word1[p:])
elif p < len(word2):
merged_string.append(word2[p:])
return "".join(merged_string)
# time complexity: On
# space: On
```
- think `pointer` at first
- learned
- 把 string 转换成 array 处理
- Complexity Analysis
- Time complexity is On
- Space complexity is On