Merge k Sorted Lists
Merge Sorted Array
Merge Two Sorted Lists
Minimum Depth of Binary Tree
category data struct
add some problems
Merge pull request #4 from usunyu/algorithm

Algorithm
Merge pull request #5 from usunyu/datastruct

category data struct
Merge pull request #6 from usunyu/interview

add some problems
Merge pull request #7 from usunyu/leetcode

Leetcode
reverse stack