Table point holds the x coordinate of some points on x-axis in a plane, which are all integers.

Write a query to find the shortest distance between two points in these points.

| x   |

|-----|

| -1  |

| 0   |

| 2   |

The shortest distance is '1' obviously, which is from point '-1' to '0'. So the output is as below:

| shortest|

|---------|

| 1       |

Note: Every point is unique, which means there is no duplicates in table point.

Follow-up: What if all these points have an id and are arranged from the left most to the right most of x axis?

Code

Note: 注意要加上 x1.x != x2.x, 否则总是0

SELECT MIN(ABS(x1.x - x2.x)) AS shortest FROM point as x1 JOIN point as x2 WHERE x1.x != x2.x