#include <stdio.h>
#include <vector>
#include <set>

using namespace std;

#define INFINITE 0x42424242

typedef vector< pair<int, int> > neighbours;

void dijkstra (int N, neighbours g[], int s, int d[])
{
  set< pair<int, int> > Q;
  for (int v=0; v<N; v++)
    d[v] = INFINITE;
  d[s] = 0;
  Q.insert(make_pair(d[s], s));
  while (!Q.empty()) {
    int u = Q.begin()->second;
    Q.erase(Q.begin());
    for (neighbours::iterator v = g[u].begin(); v != g[u].end(); v++) {
      int dv = d[u] + v->second;
      if (dv < d[v->first]) {
        if (d[v->first] != INFINITE)
          Q.erase(Q.find(make_pair(d[v->first], v->first)));
        d[v->first] = dv;
        Q.insert(make_pair(d[v->first], v->first));
      }
    }
  }
}

int main ()
{
//  FILE * f;
  int N, M, K, s, t;

  //f = fopen("newroad.in", "rt");
  scanf( "%d %d %d %d %d\n", &N, &M, &K, &s, &t);
//  fscanf(f, "%d %d %d %d %d\n", &N, &M, &K, &s, &t);
  s--; t--;
  neighbours fwd[N], rev[N];
  
  for (int i=0; i<M; i++) {
    int u, v, l;
    scanf( "%d %d %d\n", &u, &v, &l);
  //  fscanf(f, "%d %d %d\n", &u, &v, &l);
    u--; v--;
    fwd[u].push_back(make_pair(v, l));
    rev[v].push_back(make_pair(u, l));
  }

  int ds[N], dt[N];
  dijkstra(N, fwd, s, ds);
  dijkstra(N, rev, t, dt);

  int min = ds[t];
  for (int i=0; i<K; i++) {
    int u, v, l;
    scanf( "%d %d %d\n", &u, &v, &l);
//    fscanf(f, "%d %d %d\n", &u, &v, &l);
    u--; v--;
    if (ds[u] == INFINITE || dt[v] == INFINITE) continue;
    int d = ds[u] + l + dt[v];
    if (d < min) min = d;
  }
  //fclose(f);

  //f = fopen("newroad.out", "wt");
  printf( "%d\n", min);
//  fprintf(f, "%d\n", min);
  //fclose(f);

  return 0;
}
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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
}