#函数调用前，已定义s为list成员数量为MAX_N，
#f同为list，成员数量为MAX_N，每个成员为MAX_N个成员list
def stone_merge(n,a):
    for i in range(1,n+1):
        s[i] = s[i - 1] + a[i]
    for i in range(1,n+1):
        for j in range(1,n+1):
            if i == j:
                f[i][j] = 0
            else:
                f[i][j] = MAX_F #预定义的值
    for l in range(1, n):
        for i in range(1, n - l + 1):
            j = i + l
            for k in range(i,j):
                f[i][j] = min([f[i][j],f[i][k] + f[k + 1][j] + s[j] - s[i-1]])
    return f[1][n]