Data Structure and Algorithm

• Master Theorem

  

• ArrayList

  When insert or delete an element, ArrayList will create a new Array and execute a System.arraycopy. Doing those constantly will reduce efficiency.

• SkipList

  space for time | increase dimension

  multi-dimension index | log2n-dimension index

  

  Time complexity: O(log n), Space complexity: O(n)

• 283. Move Zeroes

  Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements.

  Example:

  Input: [0,1,0,3,12]
  Output: [1,3,12,0,0]
  

  Note:

  1. You must do this in-place without making a copy of the array.
  2. Minimize the total number of operations.

  class Solution {
      public void moveZeroes(int[] nums) {
          int i = 0;
          for (int j = 0; j < nums.length; j++) {
              if (nums[j] != 0) {
                  swap(nums, i, j);
                  i++;
              }
          }
      }
  
      private void swap(int[] nums, int i, int j) {
          int t = nums[i];
          nums[i] = nums[j];
          nums[j] = t;
      }
  }