144D. Missile Silos - Codeforces Solution C++ ~ CodingWithArt

➤ Problem Link : 144D. Missile Silos

✅ C++ Solution :

 
#include<bits/stdc++.h>
using namespace std;

#define ll long long int
#define pp pair<ll,ll> 
#define mp make_pair

ll n,m,s;


vector<pp> adj[200001];
ll dis[200001];

int main()
{
	ll u,v,w,l;
	cin>>n>>m>>s;
	for(int i=1;i<=n;i++)
	{
		adj[i].clear();
		dis[i]=100000000;
	}
	for(int i=1;i<=m;i++)
	{
		cin>>u>>v>>w;
		adj[u].push_back(mp(w,v));
		adj[v].push_back(mp(w,u));
	}
	cin>>l;
	dis[s]=0;
	priority_queue<pp,vector<pp>,greater<pp> > pq;
	pq.push(mp(0,s));
	pp p;
	while(!pq.empty())
	{
		p=pq.top();
		pq.pop();
		for(int i=0;i<adj[p.second].size();i++)
		{
			if(dis[adj[p.second][i].second] > dis[p.second] + adj[p.second][i].first)
			{
				dis[adj[p.second][i].second] = dis[p.second] + adj[p.second][i].first;	
				pq.push(mp(dis[adj[p.second][i].second],adj[p.second][i].second));
			}
		}
	}

	int ans1=0,ans2=0,len,d;
	for(int i=1;i<=n;i++)
	{
		if(dis[i]>l)
			continue;
		if(dis[i]==l)
			ans1++;
		else
		{
			for(int j=0;j<adj[i].size();j++)
			{
				len=adj[i][j].first;
				v=adj[i][j].second;
				d=l-dis[i];
				if(d < len)
				{
					if(dis[v]+len-d > l)
						ans1++;
					else if(dis[v]+len-d == l)
						ans2++;
				}
			}
		}
	}

	cout<<ans1+ans2/2;

}

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About Utkarsh Gupta

I am a Member Technical at D.E. Shaw India Pvt. Ltd. CodingWithArt is a blog where you find tricks and solutions to challenging coding and development problems. I aim to build a universal tech platform for every enthusiast out there.