LeetCode

My LeetCode Path and C++ language learning

Purpose

• get familiar with algorithms
• start with using java but later start to use c++

Focus Topics

• loops

• linklist
  • how it different from c as have new
  • nullptr use
  • usually return headNode->next to get rid of the default 0 pointer
• trees
• Dynamic Programming
  1. state the subproblem to solve
  2. solving the original problem by subproblems
  3. recursive formula to computer the subproblem
  • 1D array or 2D array both possible
• vector use
  • string manipulation
  • integer / string change
  • double vector (2D array)
• integer
  • overflow handle
  • INT_MAX, INT_MIN
  • module and divide
  • palindrome
• binary search
  • find mid and update low / high
  • try more use <= since = is most time handled seperately in next loop
  • try one some base case like 1/2/3 element as input
  • rotated sorted array have a part of the array sorted
• divide and conquer
  • calculate some thing about this case
  • then call max/min of three cases (left, this, right)
• priority queue
  • implemented using a heap to get the min/max
  • default is max, if want min need
  • priority_queue<int, vector, greater> heap;
    • std::priority_queue<int, std::vector, std::greater> heap;
    • push, pop, top