Since 2008, the global financial crisis has swept the world, which has brought great difficulties to China's economic development. Many small and medium-sized enterprises in coastal areas have laid off employees, resulting in a large number of unemployed people. According to relevant data, since the end of 2008, it is estimated that 20 million people have been laid off, including migrant workers100000. Although the return of some migrant workers to their hometowns can alleviate the employment pressure to some extent, more than 6 million graduates in 2009 brought great pressure to the employment market in China.

However, it is gratifying that China has huge foreign exchange reserves, abundant private capital and sufficient residents' savings. China is still a developing country, and its construction in many aspects is still at a backward level, with great investment potential. In order to maintain the rapid economic development of China, especially to solve the employment problem, it is natural to implement government investment.

At the two sessions in 2009, China officially adopted a 4 trillion investment plan, which aims to ensure GDP growth, employment and harmony. But there are several problems that have been bothering us. Please use the knowledge of mathematical modeling to solve them.

First, how many people can be employed when GDP grows by 8%? If full employment is achieved, how much will GDP increase in 2009?

Second, to achieve GDP growth of 8%, is the investment of 4 trillion enough? If not, how much investment is needed?

Third, different industries (or industries) have different ability to absorb labor and employment, so the investment flow will be different. Please make a decision. How should the 4 trillion investment be allocated to different industries (or industries) in order to maximize the employment of the labor force?

IV. Please give relevant policy suggestions (no more than 1000 words).

There is also a question about typhoons.

Read through the questions before the game. Generally, a lot of information will be revealed in the question, so as to extract information and requirements from the question and clarify the purpose.

The preparation stage is mainly to study various algorithms, methods and paper structures used in other people's papers.

1. Monte Carlo Algorithm This algorithm, also called stochastic simulation algorithm, is an algorithm to solve problems through computer simulation, and at the same time, it can test the correctness of its own model through simulation, which is almost a necessary method in the competition.

2. Data processing algorithms, such as data fitting, parameter estimation and interpolation. There are usually a lot of data to be processed in the competition, and the key to processing data lies in these algorithms, usually using MATLAB as a tool.

3. Programming algorithms, such as linear programming, integer programming, multivariate programming and quadratic programming. Most of the problems in modeling competition belong to optimization problems, and many times these problems can be described by mathematical programming algorithms, usually solved by Lindo and Lingo software.

4. Graph theory algorithm. This kind of algorithm can be divided into many kinds, including shortest path algorithm, network flow algorithm, bipartite graph algorithm and so on. Problems related to graph theory can be solved by these methods and need careful preparation.

5. Computer algorithms, such as dynamic programming, backtracking search, divide and conquer algorithm, branch and bound. These algorithms are commonly used in algorithm design and will be used in many occasions in competitions.

6. Three non-classical algorithms of optimization theory: simulated annealing algorithm, neural network algorithm and genetic algorithm. These problems are used to solve some difficult optimization problems and are very helpful to some problems, but the algorithm is difficult to implement and needs to be used carefully.

7. Grid algorithm and exhaustive method. Both of them are the best algorithms for brute force search, and they are applied in many competition questions. When we focus on the model itself and despise the algorithm, we can use this brute force scheme, and it is best to use some high-level languages as programming tools.

8. Several discretization methods of continuous data. Many problems are practical, data can be continuous, and computers can only handle discrete data, so it is very important to discretize them and implement the ideas of difference instead of differential and summation instead of integral.

9. Numerical analysis algorithm. If high-level language programming is used in the competition, the commonly used algorithms in numerical analysis, such as solving equations, matrix operation, function integration, etc., need to write additional library functions to call.

10. Image processing algorithm. There is a kind of problem related to graphics in the competition. Even if the problem has nothing to do with graphics, the paper will need pictures to illustrate the problem. How to display these graphics and how to deal with them are problems that need to be solved, which are usually handled by MATLAB.