#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
vector<pair<int, int>> v[N];
int dis[N];
bool vis[N];
void dijkstra(int s)
{
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;

    pq.push({0, s});
    dis[s] = 0;
    while (!pq.empty())
    {
        pair<int, int> parent = pq.top();
        pq.pop();
        int parentNode = parent.second;
        if (vis[parentNode])
        {
            continue;
        }
        vis[parentNode] = true;
        int parentCost = parent.first;
        for (int i = 0; i < v[parentNode].size(); i++)
        {
            pair<int, int> child = v[parentNode][i];
            int childNode = child.first;
            int childCost = child.second;
            if (parentCost + childCost < dis[childNode])
            {
                dis[childNode] = parentCost + childCost;
                pq.push({dis[childNode], childNode});
            }
        }
    }
}
int main()
{
    int n, e;
    cin >> n >> e;
    while (e--)
    {
        int a, b, w;
        cin >> a >> b >> w;
        v[a].push_back({b, w});
        // v[b].push_back({a, w});
    }
    for (int i = 1; i <= n; i++)
    {
        dis[i] = INT_MAX;
    }
    dijkstra(1);
    for (int i = 1; i <= n; i++)
    {
        cout << "Node " << i << ": " << dis[i] << endl;
    }
    return 0;
}
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C++ Online Compiler

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Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}