思路：

税+税后所得A=税前工资S。

因为工资是整百的数，每次减100来判断。好理解但是超时。

import java.util.Scanner;

//只有90分，超时了

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		int T = sc.nextInt();

		if(T < 3500) {

			System.out.println(T);

		}

		double x = 0;//税钱

		int S = 200000;//假设一个月最多挣20万

		int A = S - 3500;

		while(true)

	    {

	        if(A <= 1500)

	            x = A * 0.03;

	        else if(A <= 4500)

	            x = 45 + (A - 1500) * 0.1;

	        else if(A <= 9000)

	            x = 45 + 300 + (A - 4500) * 0.2;

	        else if(A <= 35000)

	            x = 45 + 300 + 900 + (A - 9000) * 0.25;

	        else if(A <= 55000)

	            x = 45 + 300 + 900 + 6500 + (A - 35000) * 0.3;

	        else if(A <= 80000)

	            x = 45 + 300 + 900 + 6500 + 6000 + (A - 55000) * 0.35;

	        else

	            x = 45 + 300 + 900 + 6500 + 6000 + 8750 + (A - 80000) * 0.45;

	        if(S == x + T)

	            break;

	        S = S - 100;

	        A = S - 3500;

	    }

		System.out.println(S);

	}

}