两个 flag

Given an array of ints, return true if every 2 that appears in the array is next to another 2.
twoTwo([4, 2, 2, 3]) → true
twoTwo([2, 2, 4]) → true
twoTwo([2, 2, 4, 2]) → false

Solution:

public boolean twoTwo(int[] nums) {
  boolean first2 = false;
  boolean lastIs2 = false;
  for(int val : nums) {
    if(val == 2) {
      if (lastIs2 == false && first2 == false ) {
        first2 = true;
      } else {
        first2 = false;
      }
      lastIs2 = true;
    } else {
      if(first2 == true) {
        return false;
      }
      lastIs2 = false;
    }
  }

  if(lastIs2 && first2) {
    return false;
  }

  return true;
  
}