[ymeng] use big-integer as result of power function for avoiding beyond the boundary
[ymeng] build vertical bit rectangle for insection between regions
[ymeng] Should compare area between rectangles
[ymeng] implement function of intersection between two bit rectangles
[ymeng] support place holder in bit rectangle
[ymeng] fix a mistake
[ymeng] Use same logic to merge bit rectangle and bit array
[ymeng] Use 'divide & conquer' to solve this problem
[ymeng] remove unused classes
[ymeng] call BitmapScanner in Histogram to complete this question