本文对机器学习模型评估指标进行了完整总结。机器学习的数据集一般被划分为训练集和测试集，训练集用于训练模型，测试集则用于评估模型。针对不同的机器学习问题（分类、排序、回归、序列预测等），评估指标决定了我们如何衡量...

You are trapped in a 3D dungeon and need to find the quickest way out! The dungeon is composed of unit cubes which may or may not be filled with rock. It takes ...

Given two sequences of numbers : a[1], a[2], … , a[N], and b[1], b[2], … , b[M] (1 <= M <= 10000, 1 <= N <= 1000000). Your task is to find a number K which make...

Problem Description In many applications very large integers numbers are required. Some of these applications are using keys for secure transmission of data, e...

Today is Ignatius’ birthday. He invites a lot of friends. Now it’s dinner time. Ignatius wants to know how many tables he needs at least. You have to notice tha...

Dijkstra算法应用了贪心的思想，即“抄近路走”。维护两个集合A和B，A表示已确定最短路径的结点集（红色表示）， B表示邻居结点（蓝色表示）。...

The task is simple: given any positive integer N, you are supposed to count the total number of 1's in the decimal form of the integers from 1 to N. For example...

In computer science, a heap is a specialized tree-based data structure that satisfies the heap property: if P is a parent node of C, then the key (the value) of...

首先递推公式 ： 钱币面值 从 1，一直遍历到 n , 然后兑换的面值从 j=1 到 j 等于最大的面值， 面对 第 i种面值的硬币，有两种选择，不选则当前硬币面值的所有情况 加上选择当前面值的...

对于空间数据，我们感兴趣的往往是其中的某一部分，对于不需要的部分需要做一些掩膜(Mask)。比如只关注海洋的数值变化，那么陆地上的数值对我其实是一种干扰，就要想办法掩盖掉。又比如我有全国的数据变量，但是只想研究其中某...