Actor centrality in Cplusplus

actor_centrality.cc

#include <set>
#include <string>
#include <map>
#include <fstream>
#include <iostream>
#include <vector>
#include <stdint.h>

using namespace std;

struct Node {
	string name;
	set<Node*> neighbours;
};

struct Graph {
	map<string, Node> nodes;
	vector<string> actors;
};

struct SortEntry {
	double val;
	string name;

	bool operator<(const SortEntry & other) const {
		return val < other.val;
	}
};

Graph read_graph() {
	char line[1024];
	ifstream fin;

	Graph G;
	set<string> seen_actors;

	fin.open("imdb-1.tsv");
	while (!fin.eof()) {
		string actor, movie;
		fin.getline(line, sizeof(line));
		size_t eol = strlen(line) + 1;
		int state = 0;
		size_t cs = 0;
		for (size_t i = 0; i < eol; ++i) {
			if (line[i] == '\t' or line[i] == 0) {
				line[i] = 0;
				if (state == 0) {
					actor = (line+cs);
					++state;
					cs = i+1;
				} else if (state == 1) {
					movie = (line+cs);
					++state;
					cs = i+1;
				} else if (state == 2) {
					movie += "_";
					movie += (line+cs);
					Node & an = G.nodes[actor]; an.name = actor;
					Node & mn = G.nodes[movie]; mn.name = movie;
					an.neighbours.insert(&mn);
					mn.neighbours.insert(&an);
					if (!seen_actors.count(actor)) {
						G.actors.push_back(actor);
						seen_actors.insert(actor);
					}
				}
			}
		}
	}
	return G;
}

double actor_centrality(Graph & G, string name) {
	map<Node*, uint64_t> dists;
	set<Node*> next; next.insert(&G.nodes[name]);
	set<Node*> nnext;

	set<Node*> *pnext = &next, *pnnext = &nnext;

	uint64_t cdist = 0;
	while (!pnext->empty()) {
		pnnext->clear();
		for (Node * n : *pnext) {
			if (!dists.count(n)) {
				dists[n] = cdist;
				for (Node * nn : n->neighbours) {
					if (!dists.count(nn))
						pnnext->insert(nn);
				}
			}
		}
		++cdist;
		set<Node*>* temp = pnnext;
		pnnext = pnext; pnext = temp;
	}

	double sum = 0;
	for (auto p : dists)
		sum += p.second;

	return sum / dists.size();
}
int main(int argc, char const *argv[])
{
	Graph g = read_graph();
	sort(g.actors.begin(), g.actors.end());

	vector<SortEntry> tree;

	for(int i =0; i < 100; ++i) {
		SortEntry e = {actor_centrality(g, g.actors[i]), g.actors[i]};
		cout << g.actors[i] << endl;
		tree.push_back(e );
	}
	sort(tree.begin(), tree.end());

	for(int i =1; i <=20; ++i)
		cout << i << ": " << tree[i-1].name << ", " << tree[i-1].val << endl;

	return 0;
}