2181. 合并零之间的节点 #

var mergeNodes = function(head) {
  let p = head
  while (p && p.next && !!p.next.val) {
    let p1 = p.next
    let val = 0
    while (p1 && !!p1.val) {
      val += p1.val
      p1 = p1.next
    }
    p.val = val
    p.next = p1
    if (!p1.next) {
      p.next = null
    } else {
      p = p.next
    }
  }
  return head
};