Algorithm Templates

Two Pointers / Sliding Window / Prefix Sums

• https://tianjietalk.notion.site/03-6c5caefe2f61469c81befc5a8e4f7854

  Two Pointers

  Left and Right Pointers

  public void template(int[] nums) {
    int left = 0;
    int right = nums.length - 1;
    while(left < right) {
        if () {
            left++;
        }
        if () {
            right++;
        }
    }
  }
  

Fast and Slow Pointers / Sliding Window

public void template(int[] nums) {
    int left = 0;
    int right = 1;
    while(right < nums.length) {
        if() {
            left++;
        }

        if() {
            right++;
        }
    }
}

Prefix Sums

• Main idea: the consecutive totals of the first 0, 1, 2, …, n elements of an array.
• Allow to calculate the total of any slice of the array very quickly