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C++: use refs instead of indexes #14

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9800a72
use vector instead of bitset
phiresky Dec 20, 2014
b7eea7b
C++ implementation with more refs
phiresky Dec 20, 2014
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49 changes: 15 additions & 34 deletions cpp.cpp
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Original file line number Diff line number Diff line change
@@ -1,20 +1,21 @@
#include <ctime>
#include <vector>
#include <bitset>
#include <fstream>
#include <iostream>
#include <string>
#include <chrono>

using namespace std;
using namespace std::chrono;

struct node;

struct route{
int dest, cost;
node& dest;
const int cost;
};

struct node {
vector<route> neighbours;
bool visited = false;
};

vector<node> readPlaces(){
Expand All @@ -23,50 +24,30 @@ vector<node> readPlaces(){
vector<node> nodes(numNodes);
int node, neighbour, cost;
while (text >> node >> neighbour >> cost){
nodes[node].neighbours.push_back(route{neighbour, cost});
nodes[node].neighbours.push_back(route{nodes[neighbour], cost});
}
return nodes;
}

template <int T>
int getLongestPath(const vector<node> &nodes, const int nodeID, bitset<T> visited){
visited[nodeID] = true;
int getLongestPath(vector<node> &nodes, node &node){
node.visited = true;
int max=0;
for(const route &neighbour: nodes[nodeID].neighbours){
if (visited[neighbour.dest] == false){
const int dist = neighbour.cost + getLongestPath<T>(nodes, neighbour.dest, visited);
for(const route &neighbour: node.neighbours){
if (!neighbour.dest.visited){
const int dist = neighbour.cost + getLongestPath(nodes, neighbour.dest);
if (dist > max){
max = dist;
}
}
}
visited[nodeID] = false;
node.visited = false;
return max;
}

int getLongestPath(const vector<node> &nodes)
{
if (nodes.size() <= 16) {
return getLongestPath<16>(nodes, 0, bitset<16>());
} else if (nodes.size() <= 256) {
return getLongestPath<256>(nodes, 0, bitset<256>());
} else if (nodes.size() <= 4096) {
return getLongestPath<4096>(nodes, 0, bitset<4096>());
} else if (nodes.size() <= 65536) {
return getLongestPath<65536>(nodes, 0, bitset<65536>());
} else if (nodes.size() <= 1048576) {
return getLongestPath<1048576>(nodes, 0, bitset<1048576>());
} else if (nodes.size() <= 16777216) {
return getLongestPath<16777216>(nodes, 0, bitset<16777216>());
} else {
return -1;
}
}

int main(int argc, char** argv){
auto nodes = readPlaces();
int main() {
vector<node> nodes = readPlaces();
auto start = high_resolution_clock::now();
int len = getLongestPath(nodes);
int len = getLongestPath(nodes, nodes[0]);
auto end = high_resolution_clock::now();
auto duration = (int)(0.001 * duration_cast<microseconds>(end - start).count());
cout << len << " LANGUAGE C++ " << duration << std::endl;
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