separate problems

array - O(nlogn) O(n)

added solutions in java

backtracking recursion - O(2^n) O(1)

string - 2 pointers recursion O(s.len^tokens)

string - 2 pointers O(n) O(n)

string hashmap - 2 pointers recursion O(s.len^tokens)

changed file name

string hash map - 2 pointers O(n) O(n)

doubly linked list - O(1)/O(n) O(1)/O(n)

doubly linked list - O(1) O(1)

lru cache like - array O(n) O(1)

tree - dfs recu O(nodes) O(tree height + nodes)

changed file name

added google questions

binary exponentiation - O(logn) O(1)

binary tree - dfs iter O(nlogn) O(n)

graph - dfs recu O(edges) O(nodes)

graph - dfs recu O(edges) O(nodes)

string - 2 pointers O(n) O(n)

array - 2 pointers O(n) O(1)

binary tree - bfs iter + dfs recu O(n) O(n)

renamed folder

renamed folder

linked list - iter O(n) O(1)

array - sort O(nlogn) O(n)

string - O(1) O(1)

string - O(rxc) O(rxc)

didnt pass all tests

array - recu O(2^n) O(2^n)