2018-04-25

比较失落吧,算法确实需要保持日常，这样才有感觉，今晚两题leetcode easy的题都没做好，第一题没审好题，导致用了太多时间，第二题都没做好，记录一下这两题吧。

Longest String Prefix

var longestPrefix = function(s) {
  let maxLength = 0;
  if (!s || s.length === 0) {
    return maxLength;
  }
  for (let i = 0; i < s.length - 1; i++) {
    if (s.charCodeAt(i) <= s.charCodeAt(i + 1)) {
      maxLength += 1;
    } else {
      break;
    }
  }
  return maxLength > 0 ? maxLength + 1 : maxLength;
};

Swap Nodes

var swapNodes = function(head, k) {
  let leftCursor,
    rightCursor,
    cursor = head,
    count = 1,
    queue = [];
  while (cursor) {
    queue.unshift(cursor);
    let length = queue.length;
    if (length === k) {
      leftCursor = queue[length - 1];
    }
    cursor = cursor.next;
  }
  rightCursor = queue[k];
  // 真实需要交换的节点
  let r = rightCursor.next,
    l = leftCursor.next,
    temp = r.next;
  r.next = l.next;
  leftCursor.next = r;
  rightCursor.next = l;
  l.next = temp;
  return head;
};