Codeforces celebrates 10 years! We are pleased to announce the crowdfunding-campaign. Congratulate us by the link https://codeforces.com/10years. ×

By eblabrada_, history, 2 months ago, , These algorithms operate on an array and are useful in saving time during coding and hence useful in competitive programming as well.

all_of() : This function operates on whole range of array elements and can save time to run a loop to check each element one by on. It checks for a given property on every element and returns true when each element in range satisfies specified property, else returns false.

#include <bits/stdc++.h>

using namespace std;

int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);

// Initializing array
int arr = {1, 2, 3, 4, 5, -6};

// Checking if all elements are odds.
bool ans = all_of(arr, arr + 6, [](int x) {return x & 1; } );

if (ans){
cout << "All are odds numbers\n";
}
else{
cout << "All are not odds numbers\n";
}

// Output:
// All are not odds numbers.

return 0;
}



any_of() : This function checks for a given range if there’s even one element satisfying a given property mentioned in function. Returns true if at least one element satisfies the property else returns false.

#include <bits/stdc++.h>

using namespace std;

int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);

// Initializing array
int arr[] = {1, 2, 3, 4, 5, -6};

// Checking if any element is negative.
bool ans = any_of(arr, arr + 6, [](int x) {return x < 0; } );

if (ans){
cout << "There are exists a negative element\n";
}
else{
cout << "All are positive elements\n";
}

// Output:
// There are exists a negative element

return 0;
}



none_of() : This function returns true if none of element satisfies the given condition else returns false.

#include <bits/stdc++.h>

using namespace std;

int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);

// Initializing array
int arr[] = {1, 2, 3, 4, 5, -6};

// Checking if no element is negative.
bool ans = none_of(arr, arr + 6, [](int x) {return x < 0; } );

if (ans){
cout << "No negative elements\n";
}
else{
cout << "There are negative element\n";
}

// Output:
// There are negative element

return 0;
}



copy_n() : copies one array elements to new arrays. This type of copy creates a deep copy of array. This function takes 3 arguments, source array name, size of array and the target array name.

#include <bits/stdc++.h>

using namespace std;

int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);

// Initializing array
int arr[] = {1, 2, 3, 4, 5, -6};

// Declaring second array
int ans;

copy_n(arr, 6, ans);

cout << "The new array after copying is: ";

for (int i = 0; i < 6; i++){
cout << ans[i] << " ";
}

cout << "\n";

// Output:
// The new array after copying is: 1 2 3 4 5 -6

return 0;
}



iota() : This function is used to assign continuous values to array. This function accepts 3 arguments, the array name, size, and starting number.

#include <bits/stdc++.h>

using namespace std;

int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);

// Initializing array
int arr = {0};

// Using iota() to assign values
iota(arr, arr + 6, 20);

// Displaying the new array
cout << "The new array after assigning values is: ";

for (int i = 0; i < 6; i++){
cout << arr[i] << " ";
}

cout << "\n";

// Output:
// The new array after assigning values is: 20 21 22 23 24 25

return 0;
}



accumulate() : This function returns the sum of all the values lying in a range between [first, last) with the variable sum.

#include <bits/stdc++.h>

using namespace std;

int fun (int x, int y){
return x * y;
}

int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);

int sum = 1;
int arr[] = {5, 10, 15};

// Simple default accumulate function
cout << "Result using accumulate: ";
cout << accumulate(arr, arr + 3, sum) << "\n";

// Using accumulate function with user-defined function
cout << "Result using accumulate with user-defined function: ";
cout << accumulate(arr, arr + 3, sum, fun) << "\n";

// Using accumulate function with pre-defined function
cout << "Result using accumulate with pre-defined function ";
cout << accumulate(arr, arr + 3, sum, minus<int>()) << "\n";

// Output:
// Result using accumulate: 31
// Result using accumulate with user-defined function: 750
// Result using accumulate with pre-defined function -29

return 0;
}



Thank you all !!!

By eblabrada_, history, 3 months ago, , Hello everyone!

I am glad to invite you to Data Structures' Contest #1, which will take place on Saturday, December 7, 2019 at 15:00 UTC-5

I have learned a lot of things on the last months and have much fun in participating in the competitions. Now, I want to contribute to the community by proposing some problems from data structures. I hope that you will find something interesting in solving them.

There will be roughly 7 problems.

Good luck to the participants!! See you on the scoreboard.