Dijkstra

PHOTO EMBED

Thu Sep 07 2023 13:58:18 GMT+0000 (Coordinated Universal Time)

Saved by @psisodiyaparek #c++ 

#include <iostream>
#include <set>
#include <algorithm>
#include <math.h>
#include <vector>
#include <queue>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <iterator>
// #include<bits/stdc++.h>
using namespace std;
#define forn(i, a, n) for (int i = a; i < n; i++)
#define MAXN 1000000
#define MOD 1000000007
#define INT_MAX 1e12
#define int long long
#define tc    \
    int t;    \
    cin >> t; \
    while (t--)
#define TC size(arr) / size(arr[0])
#define Radhe ios::sync_with_stdio(false);
#define Krishna cin.tie(NULL);
void solve()
{
    int n, m;
    cin >> n >> m;
    vector<vector<pair<int, int>>> adj(n);
    map<pair<int, int>, int> mp;
    vector<int> par(n, -1);
    for (int i = 0; i < m; i++)
    {
        int u, v, w;
        cin >> u >> v >> w;
        if (u == v)
        {
            continue;
        }
        if (v < u)
        {
            swap(u, v);
        }
        u--, v--;
        
        
        if (mp.count({u, v}))
        {
            mp[{u, v}] = min(mp[{u, v}], w);
        }
        else
        {
            mp[{u, v}] = w;
        }
    }
    
for  (auto i = mp.begin(); i != mp.end(); i++) 
    { auto x=*i;
        adj[x.first.first].push_back({x.first.second,x.second});
        adj[x.first.second].push_back({x.first.first,x.second});
    }

    priority_queue<pair<int, pair<int, int>>, vector<pair<int, pair<int, int>>>, greater<pair<int, pair<int, int>>>> pq;
    vector<int> dist(n, INT_MAX);
    dist[0] = 0;
    pq.push({0, {0, -1}});
    while (!pq.empty())
    {
        int u = pq.top().second.first;
        if(pq.top().first>dist[u])
        {
            pq.pop();
            continue;
        }
        par[u] = pq.top().second.second;
        pq.pop();
        for (auto it : adj[u])
        {
            int v = it.first;
            int weight = it.second;
            if (dist[u] == INT_MAX)
            {
                continue;
            }
            if (dist[v] > dist[u] + weight)
            {
                dist[v] = dist[u] + weight;
                pq.push({dist[v], {v, u}});
            }
        }
    }
   
    if(dist[n-1]==INT_MAX)
    {
        cout<<-1<<endl;
        return;
    }
    vector<int> ans;
    int i = n - 1;
    while (i != -1)
    {
        ans.push_back(i + 1);
        i = par[i];
    }
    for(int i=ans.size()-1;i>0;i--)
    {
        cout<<ans[i]<<" ";
    }
    cout<<ans[0]<<endl;
}
int32_t main()
{
    Radhe Krishna
    {
        solve();
    }

    return 0;
}
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