Array题型：双指针Two Pointers套路

一、反向

 

通用步骤：

1. Initialize two pointer i = 0, j = array.length - 1
2. while i <= j: 
   • Decide what you should do based on the value of array[i] and array[j]
   • Move at least one pointer forward in its direction

二、同向

通用步骤：

1. Initialize two pointers i and j, usually both equal to 0
2. while i < array.length:
   1. if we need array[i], then we keep it by assigning array[i] = array[j], and move i forward, make it ready at the next position
   2. otherwise skip it. We do not need to move i since its spot is not fulfilled