字符串

[541] 反转字符串 II

var reverseStr = function (s, k) {
  let i = 0;
  let result=s.split('') //因为字符串是不可变的，无法修改原字符串
  const length = result.length;
  while (i < length) {
    let left = i,
      right = i + k - 1 < length ? i + k - 1 : length - 1;
    while (left <= right) {
      [result[left],result[right]]=[result[right],result[left]]
      left++;
      right--;
    }
    i += 2 * k;
  }
  return result.join('');
};