// There are given n ropes of different lengths, we need to connect these ropes into one rope. The cost to connect two ropes is equal to sum of their lengths. We need to connect the ropes with minimum cost.

// For example if we are given 4 ropes of lengths 4, 3, 2 and 6. We can connect the ropes in following ways.
// 1) First connect ropes of lengths 2 and 3. Now we have three ropes of lengths 4, 6 and 5.
// 2) Now connect ropes of lengths 4 and 5. Now we have two ropes of lengths 6 and 9.
// 3) Finally connect the two ropes and all ropes have connected.

// Total cost for connecting all ropes is 5 + 9 + 15 = 29. This is the optimized cost for connecting ropes. Other ways of connecting ropes would always have same or more cost. For example, if we connect 4 and 6 first (we get three strings of 3, 2 and 10), then connect 10 and 3 (we get two strings of 13 and 2). Finally we connect 13 and 2. Total cost in this way is 10 + 13 + 15 = 38. . 


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

class solution{
  public:
  void FindMinimumCost(int arr[], int n){
    priority_queue<int,vector<int>, greater<int>>min_heap;
    for(int i=0; i<n; i++){
      min_heap.push(arr[i]);
    }
    int cost = 0;
    while(min_heap.size()>1){
      int a = min_heap.top();
      min_heap.pop();
      int b = min_heap.top();
      min_heap.pop();
      cost += a+b;
      min_heap.push(a+b);
    }
    cout<<cost;
    min_heap.pop();
  }
};

int main() 
{
   int n;
   cin>>n;
   int arr[n];
   for(int i=0; i<n; i++){
     cin>>arr[i];
   }
   solution ob;
   ob.FindMinimumCost(arr, n);
}
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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
}