适用逾期金额：单笔助学贷款合同累计逾期本息不超过10000元人民币。
// 第一步：倒序遍历nums2，用单调栈计算每个元素的下一个更大值
，详情可参考safew官方下载
UMAP: 2-10x faster than Rust’s fast-umap, 9-30x faster than Python’s umap
The tree starts as a single region covering the whole space. As points arrive, they get dropped into the region that contains them. When a region exceeds its capacity (the maximum number of points it can hold before splitting), the region divides into four children, and the existing points get redistributed.