+-------------+------+?

| Column Name | Type |?

+-------------+------+?

| power ? ? ? | int ?|?

|factor ? ? ?| int ?|

+-------------+------+

power is the primary key column for this table.?

Each row of this table contains information about one term of the equation.?

power is an integer in the range [0, 100].

factor is an integer in the range [-100, 100] and cannot be zero.

You have a very powerful program that can solve any equation of one variable in the world. The equation passed to the program has to follow the following rules: The LHS should contain all the terms.?

The RHS should be zero.

Each term of the LHS should follow the format "sign factor X ^power" after removing the white spaces where: sign is either "+" or "-". factor is the absolute value of the factor.

power is the value of the power.?

If the power is 1, do not add "^power".?

For example, if power = 1 and factor = 3, the term will be "+3X".?

If the power is 0, add neither "X" nor "^power".?

For example, if power = 0 and factor = -3, the term will be "-3".

The powers in the RHS should be sorted in descending order.

Write an SQL query to build the equation.?

The query result format is in the following example.

Terms table:?

+-------+--------+?

| power | factor |

+-------+--------+?

| 2 ? ? | 1 ? ? ?|

| 1 ? ? | -4 ? ? |

| 0 ? ? | 2 ? ? ?|

+-------+--------+

Output:?

+--------------+

| equation ? ? |

+--------------+?

| +1X^2-4X+2=0 |?

+--------------+

Example 2:?

Input:

Terms table:

+-------+--------+?

| power | factor |

+-------+--------+?

| 4 ? ? | -4 ? ? |

| 2 ? ? | 1 ? ? ?|?

| 1 ? ? | -1 ? ? |

+-------+--------+

Output:

+-----------------+?

| equation ? ? ? ?|

+-----------------+?

| -4X^4+1X^2-1X=0 |?

+-----------------+

主要用自聯(lián)接，stuff for xml path 還有convert? 0的情況沒單獨驗證，后面有機會驗證一下，太困了。