Dijkstra in C++

Published on 28 April 2022 (Updated: 27 November 2022)

Dijkstra in C++

Welcome to the Dijkstra in C++ page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

#include <bits/stdc++.h>
#define pii pair<int, int>
using namespace std;

const int N = 7;
bool vis[N];
vector<pii> g[N];
vector<int> dis(N, INT_MAX);

void handle_error()
{
    cout << "Usage: please provide three inputs: a serialized matrix, a source node and a destination node";
    exit(0);
}

int check(string s)
{
    int x1 = 0, x2 = (int)s.size() - 1;

    for (int i = 0; i < s.size(); i++)
    {
        if (s[i] != ' ')
        {
            x1 = i;
            break;
        }
    }

    for (int i = (int)s.size() - 1; i >= x1; i--)
    {
        if (s[i] != ' ')
        {
            x2 = i;
            break;
        }
    }

    for (int i = x1; i <= x2; i++)
    {
        if (s[i] == ' ')
        {
            handle_error();
        }
    }

    return stoi(s);
}

vector<int> convert(string s)
{

    if (s.size() == 0)
    {
        handle_error();
    }
    vector<int> v;
    string num = "";
    for (int i = 0; i < s.size(); i++)
    {
        if (((int)s[i] >= 48 && (int)s[i] <= 57) || s[i] == ' ' || s[i] == '-')
        {
            num += s[i];
        }
        else if (s[i] == ',')
        {
            int x = check(num);
            if (x < 0)
                handle_error();
            v.push_back(x);
            num = "";
        }
    }

    if (num.size() > 0)
    {
        int x = check(num);
        if (x < 0)
            handle_error();
        v.push_back(x);
    }

    return v;
}

vector<int> dijkstra(int src)
{
    set<pii> s;
    s.insert({dis[src], src});
    while (!s.empty())
    {
        pii tp = *s.begin();
        int tpn = tp.second, tpd = tp.first;
        s.erase({tpd, tpn});
        for (auto it : g[tpn])
        {
            int chd = it.second;
            int chn = it.first;
            if (tpd + chd < dis[chn])
            {
                auto it = s.find({dis[chn], chn});
                if (it != s.end())
                    s.erase(it);
                dis[chn] = tpd + chd;
                s.insert({dis[chn], chn});
            }
        }
    }
    return dis;
}

int main(int argc, char *argv[])
{

    if (argc <= 1)
        handle_error();
    vector<int> bin = convert(argv[1]), nodes = convert(argv[2]), t = convert(argv[3]);
    if (bin.size() == 0 || nodes.size() == 0 || t.size() == 0)
        handle_error();
    int des = t[0];
    int src = nodes[0];
    if (src < 0 || des < 0)
        handle_error();

    int sz = sqrt((int)bin.size());
    if (sz * sz != bin.size())
        handle_error();
    int k = 0;
    for (int i = 0; i < bin.size(); i += sz)
    {
        for (int j = i; j < i + sz; j++)
        {
            if (bin[j] < 0)
                handle_error();
            if (bin[j] != 0)
            {
                g[j - sz * k].push_back({k, bin[j]});
                g[k].push_back({j - sz * k, bin[j]});
            }
        }
        k++;
    }

    dis[src] = 0;
    vector<int> ans = dijkstra(src);
    if (dis[des] == INT_MAX)
        handle_error();
    cout << ans[des] << "\n";
}

Dijkstra in C++ was written by:

If you see anything you'd like to change or update, please consider contributing.

Note: The solution shown above is the current solution in the Sample Programs repository as of Oct 10 2022 16:05:09. The solution was first committed on Oct 06 2022 05:06:52. As a result, documentation below may be outdated.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.