#include <iostream>
#include <vector>
#include <deque>
#include <cmath>
#include <unordered_map> 
using namespace std;


int rand7(){
  return rand() % 7 + 1;
}

int rand10(){
  int res;
  while(true){
     res = (rand7() - 1)*7  + rand7();
     if(res <= 40) break;
  }
  return res%10 + 1;
}


vector<int> countBits(int num){
  vector<int> dp(num+1, 0);
  for(int i= 1; i<= num; ++i){
    dp[i] = i & 1 ? dp[i-1] + 1: dp[i>>1]; 
  }
  return dp;
}



vector<int> maxSlidingWindow(vector<int>& nums, int k){
  std::deque<int> dq;
  vector<int> ans;
  for(int i=0; i< nums.size(); ++i){
    if(!dq.empty() && dq.front() == i-k){
      dq.pop_front();
    }
    
    while(!dq.empty() && nums[dq.back()] < nums[i]){
      dq.pop_back();
    }
    
    dq.push_back(i);
    
    //collect ans
    if(i>= k-1){
      ans.push_back(nums[dq.front()]);
    }
    
  }
}


int subarraySum(vector<int>& nums, int k)
{
  int count = 0;
  int psum  = 0;
  unordered_map<int, int> hashmap;
  hashmap[0] = 1; 
  for(int  i: nums){
    psum +=  i;
    count += hashmap[psum-k];
    ++hashmap[psum];
  }
  return count;
}




int main() 
{
    for(int i=0; i< 10; ++i)
    cout << rand10() << endl;
    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
}