704.二分查找

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number}
 */
var search = function (nums, target) {
  let l = 0, r = nums.length - 1, tmp;
  while (l <= r) {
    tmp = Math.floor((l + r) / 2);
    if (nums[tmp] < target) l = tmp + 1;
    else if (nums[tmp] > target) r = tmp - 1;
    else return tmp;
  }
  return -1;
};