给定n个大小不等的圆c1,c2,c3,...,cn,现要将这n个圆排进一个矩形框中，且要求各圆与矩形框的底边相切。圆排列问题要求从n个圆的所有排列中找出有最小长度的圆排列。编程任务：对于给定的n个圆，设计算法，计算n个圆的最佳排列方案，使其长度达到最小。
输入:第一行有1个正整数n (圆的个数1≤n≤20)
接下来的1行有n个数，表示n个圆的半径
输出:将计算出的最小圆排列的长度(保留2位小数)
例如:
输入:
3
1 1 2
输出:
7.66

,Given n-size circle c1, c2, c3 ,..., cn, is a circular to this n into a rectangular box, and asked to circle and tangent to the bottom edge of the rectangular box. With the issue of yen from the n-all arranged in a circle to identify the length of the circle with the smallest. Programming tasks: for a given round of the n-designed algorithm to calculate the best n-round with programs to minimize the length. Input: the first line there is a positive integer n (the number of round 1 ≤ n ≤ 20) then there is n number of line 1, that n the radius of a circle Output: the minimum will be calculated with the length of a round (reservations 2 decimal) For example: Input: 3 1 1 2 output: 7.66