二分搜索——34. Search for a Range

34. Search for a Range

Given an array of integers sorted in ascending order, find the starting and ending position of a given target value.

Your algorithm's runtime complexity must be in the order of O(log n).

If the target is not found in the array, return [-1, -1].

For example,
Given [5, 7, 7, 8, 8, 10] and target value 8,
return [3, 4].

  var searchRange = function(nums, target) {        var left = 0,            len = nums.length,            right = len - 1,            middle = -1;        while (left <= right) {            middle = Math.floor(left + (right - left) / 2);            if (nums[middle] > target) {                right = middle - 1;            } else if (nums[middle] < target) {                left = middle + 1;            } else {                var i = middle,                    ci = middle,                    j = middle,                    cj = middle;                while ((i >= 0 && nums[i] == target) || (j <= len && nums[j] == target)) {                    i--;                    j++;                    if (i >= 0 && nums[i] == target) {                        ci = i;                    }                    if (j >= 0 && nums[j] == target) {                        cj = j;                    }                }                return [ci, cj];            }        }        return [-1, -1];    };