符号平衡问题:给定n 个整数n a , a , ,a 1 2  组成的序列，试设计一个O(n)时间算法，计算其最长符号 平衡段的长度。-Symbol balance: Given n integers na, a,, a 1 2  composed of a sequence and try to design an O (n) time algorithm to calculate the balance of the longest segment of t