【两种解法】Quadtrees UVA - 297（隐式建树+显式建树）
立志用最少的代码做最高效的表达A quadtree is a representation format used to encode images. The fundamental idea behind the quadtree is that any image can be split into four quadrants. Each quadrant may again be split in four sub quadrants, etc. In the quadtree, the
