Nicksxs's Blog

Number of 1 Bits

Write a function that takes an unsigned integer and returns the number of ’1’ bits it has (also known as the Hamming weight). For example, the 32-bit integer ‘11’ has binary representation 00000000000000000000000000001011, so the function should return 3.

Pcre

Perl Compatible Regular Expressions (PCRE) is a regular
expression C library inspired by the regular expression
capabilities in the Perl programming language, written
by Philip Hazel, starting in summer 1997.

因为最近工作内容的一部分需要做字符串的识别处理，所以就顺便用上了之前在PHP中用过的正则，在C/C++中本身不包含正则库，这里使用的pcre，对MFC开发，在这里提供了静态链接库，在引入lib跟.h文件后即可使用。

problem

Given an array of integers, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.

problem

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

problem

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Clone a graph. Input is a Node pointer. Return the Node pointer of the cloned graph.

A graph is defined below:
struct Node {
vector neighbors;
}