186. Reverse Words in a String I

按照单词反转字符串，再整体反转

• 时间复杂度O(n)，空间复杂度O(1)
• Runtime: 88 ms, faster than 99.40%
• Memory Usage: 46.2 MB, less than 31.74%

/**
 * @param {character[]} s
 * @return {void} Do not return anything, modify s in-place instead.
 */
var reverseWords = function(s) {
  s = s.reverse();
  let left = 0;
  for (let i = 0; i < s.length; i++) {
    if(s[i + 1] === ' ' || s[i + 1] === undefined) {
      let right = i;
      while(left < right) {
        let tmp = s[left];
        s[left++] = s[right];
        s[right--] = tmp
      }
      left = i + 2;
    }
  }
  return s;
};