new file:   .clang-format
new file:   leetcode/preorderTraversal.cpp
new file:   leetcode/wordBreak4.cpp
new file:   leetcode/wordBreak4_2.cpp
new file:   inorderTraversal.cpp
new file:   postorderTraversal.cpp
new file:   postorderTraversal2.cpp
new file:   postorderTraversal3.cpp
new file:   postorderTraversal4.cpp
new file:   postorderTraversal5.cpp