圖像來源，Getty Images
Prostate cancer
。业内人士推荐同城约会作为进阶阅读
Why is this a problem?
圖像來源，Getty Images
The spatial view (the grid of rectangles) and the tree view (the hierarchy of nodes) represent the same structure. Searching for a point means walking down the tree: at each node, you check which of the four children contains your target coordinate and recurse into that child. You never visit the other three.