PageRank算法C++代码实现标准版

对于PageRank算法，维基百科和网上很多大牛的博客已经讲得很详细了，这里附上一个自己写的PageRank算法C++实现版本：

/** Author: YANG Xiangyu* The Chinese university of Hong Kong*/#include<cstdio>#include<iostream>#include<fstream>#include<cstdlib>#include<string>#include<algorithm>using namespace std;#define MAX 1000000struct edge//define edge{int u;int v;}edge[5200000];int rednum[MAX]={0};//to mark a point that if it has been visited, and record a new numberint orinum[MAX]={0};//to record the original number of the new recorded numberint d[MAX]={0};//to mark the out degree of the pointdouble ra[MAX]={0};//to mark the current rank value of the pointdouble rb[MAX]={0};//to mark the updated rank value of the pointint cmp(const int &a, const int &b){if(ra[rednum[a]]>ra[rednum[b]])return 1;return 0;}void pagerank(){ifstream fin("D:\\web-Google.txt");//If TA want to test my code, please take the text 'web-google.txt' to the D disk.ofstream fout("D:\\output.txt");memset(edge,0,sizeof(edge));string s;for(int i=0;i<4;++i){getline(fin,s);cout<<s<<endl;}//Read the first four lines of the input fileint ncnt=0;int ecnt=0;int cnt=0;double eps=0.1;double flag;int i;for(i=0;fin>>edge[i].u>>edge[i].v;++i)//input the two point of each edge{if(!rednum[edge[i].u]) //judge the point whether it has been visited {rednum[edge[i].u]=ncnt;//redefine the number of current pointorinum[ncnt++]=edge[i].u;//record the original number of current point}if(!rednum[edge[i].v]) //judge the point whether it has been visited{rednum[edge[i].v]=ncnt;//redefine the number of current pointorinum[ncnt++]=edge[i].v;//record the original number of current point}d[rednum[edge[i].u]]++;}ecnt=i;printf("%d %d\n",ncnt,ecnt);for(i=0;i<ncnt;++i)ra[i]=(double)1/ncnt;while(eps>0.0000001)//set ε=10^(-7), control the number of iterations{printf("%d %.7lf\n",cnt,eps);eps=0;cnt++;for(int i=0;i<ecnt;++i)rb[rednum[edge[i].v]]+=ra[rednum[edge[i].u]]/d[rednum[edge[i].u]]; //first step to initialize the rank valuefor(int i=0;i<ncnt;++i){rb[i]=rb[i]*0.8+(0.2*1/ncnt); //add the random jumping coefficient β, and set β=0.8eps+=ra[i]>rb[i]?(ra[i]-rb[i]):(rb[i]-ra[i]);//compute the Difference between the old rank value and new rank value, and update the εra[i]=rb[i];rb[i]=0;}}sort(orinum,orinum+ncnt,cmp);//sort the array according to the scorefor(int i=0;i<100;++i)fout<<orinum[i]<<' '<<ra[rednum[orinum[i]]]<<endl;}int main(){pagerank();return 0;}