SOURCE

//思路：
//对于已排序数组
//1.元素大于左边最大值
//2.元素小于右边的最小值
//所以找到元素位置满足
//1.元素比左边的最大值还小
//2.元素比右边的最小值还大
var findUnsortedSubarray = function(nums) {
        var len = nums.length,
            beg = -1,
            end = -2,
            max = nums[len - 1],
            min = nums[0];
        for (var i = 0; i < len; i++) {
            var before = nums[i],
                after = nums[len - 1 - i];

            if (before < min) {
                end = i;
            } else {
                min = before;
            }
            if (after > max) {
                beg = len - 1 - i;
            } else {
                max = after;
            }
            console.log(end, beg);
        }
        return end - beg + 1;
    };
    console.log(findUnsortedSubarray([1, 6, 7, 8, 5, 2]));