Painting Eggs

The Bitlandians are quite weird people. They have very peculiar customs.

As is customary, Uncle J. wants to have n eggs painted for Bitruz (an ancient Bitland festival). He has asked G. and A. to do the work.

The kids are excited because just as is customary, they're going to be paid for the job!

Overall uncle J. has got n eggs. G. named his price for painting each egg. Similarly, A. named his price for painting each egg. It turns out that for each egg the sum of the money both A. and G. want for the painting equals 1000.

Uncle J. wants to distribute the eggs between the children so as to give each egg to exactly one child. Also, Uncle J. wants the total money paid to A. to be different from the total money paid to G. by no more than 500.

Help Uncle J. Find the required distribution of eggs or otherwise say that distributing the eggs in the required manner is impossible.

Input

The first line contains integer n (1 ≤ n ≤ 106) — the number of eggs.

Next n lines contain two integers ai and gi each (0 ≤ ai, gi ≤ 1000; ai + gi = 1000)aiis the price said by A. for the i-th egg and gi is the price said by G. for the i-th egg.

Output

If it is impossible to assign the painting, print "-1" (without quotes).

Otherwise print a string, consisting of n letters "G" and "A". The i-th letter of this string should represent the child who will get the i-th egg in the required distribution. Letter "A" represents A. and letter "G" represents G. If we denote the money Uncle J. must pay A. for the painting as Sa, and the money Uncle J. must pay G. for the painting as Sg, then this inequality must hold: |Sa  -  Sg|  ≤  500.

If there are several solutions, you are allowed to print any of them.

Example
Input
2
1 999
999 1
Output
AG
Input
3
400 600
400 600
400 600
Output

AGA


题意:有n个鸡蛋,分给A和G两个人,每个人的对每个鸡蛋的价格不同,如何分配能保证|Sa - Sg|<=500。


Select Code

#include <stdio.h>
int main()
{
    int i,n,a=0,g=0,flag=1;
    char b[1000010];
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
    int x,y;
    scanf("%d %d",&x,&y);
    if(a+x-g<=500)
        {
        a+=x;
        b[i]='A';
    }
    else if(g+y-a<=500)
        {
            g+=y;
            b[i]='G';
        }
    else
        {
            flag=0;
            break;
        }
    }
    if(flag)
    {
    for(i=0;i<n;i++)
    {
        printf("%c",b[i]);
    }
    }
    else
    {
        printf("-1\n");
    }
        return 0;
}

内容概要:本文介绍了一种利用元启发式算法(如粒子群优化,PSO)优化线性二次调节器(LQR)控制器加权矩阵的方法,专门针对复杂的四级倒立摆系统。传统的LQR控制器设计中,加权矩阵Q的选择往往依赖于经验和试错,而这种方法难以应对高维度非线性系统的复杂性。文中详细描述了如何将控制器参数优化问题转化为多维空间搜索问题,并通过MATLAB代码展示了具体实施步骤。关键点包括:构建非线性系统的动力学模型、设计适应度函数、采用对数缩放技术避免局部最优、以及通过实验验证优化效果。结果显示,相比传统方法,PSO优化后的LQR控制器不仅提高了稳定性,还显著减少了最大控制力,同时缩短了稳定时间。 适合人群:控制系统研究人员、自动化工程专业学生、从事机器人控制或高级控制算法开发的技术人员。 使用场景及目标:适用于需要精确控制高度动态和不确定性的机械系统,特别是在处理多自由度、强耦合特性的情况下。目标是通过引入智能化的参数寻优手段,改善现有控制策略的效果,降低人为干预的需求,提高系统的鲁棒性和性能。 其他说明:文章强调了在实际应用中应注意的问题,如避免过拟合、考虑硬件限制等,并提出了未来研究方向,例如探索非对角Q矩阵的可能性。此外,还分享了一些实践经验,如如何处理高频抖动现象,以及如何结合不同类型的元启发式算法以获得更好的优化结果。
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