How to integrate a row in pascal's triangle? - c++

Question

I have a pascal's triangle with max rows of 5 . Lets suppose I want to find the integration of the fourth row . How do I access the fourth row in the pascal's triangle. More precisely I want to know how to access a row in the pascal's triangle by entering the number n of the row
Code
#include <iostream>
using namespace std;
int main(){
int a1, a2, a3, a4, a5, pascal, columns;
const int rows = 5;
int **array = new int *[rows]; //generating array
for(int i = 0; i <= rows; i++)
array[i] = new int [columns];
for (int i = 0; i <= rows; i++){ //loop for te pascal's triangle
for (int j = 0; j <= i; j++){
if(j == 0 || i == 0){
pascal = 1; //first element of pascal's triangle
}
else{
pascal = pascal *(i - j + 1) / j; //pascal's triangle formula
}
cout << " " << pascal; // printing pascals triangle
}
cout << "\n";
}
cout << "enter which row to integrate: ";
// here I want to directly access a row rather that entering the elements of the row
cin >> a1;
cin >> a2;
cin >> a3;
cin >> a4;
cin >> a5;
}
1
1 1
1 2 1
1 3 3 1 ------> like of n = 4 i want to integrate the elements of this row
1 4 6 4 1
And the answer should be for 1,3,3,1 = 0, 1, 1.5, 1, 0.25

Answer 1

you should first fill the array with the elements then you can access them like so (EDIT: Make sure to initialize the columns variable, I set it to 5)
#include <iostream>
using namespace std;
int main() {
int row_nb, pascal, columns = 5; //Initialized columns with columns = 5
const int rows = 5;
int **array = new int *[rows]; //generating array
for (int i = 0; i <= rows; i++)
array[i] = new int[columns];
for (int i = 0; i <= rows; i++) { //loop for te pascal's triangle
for (int j = 0; j <= i; j++) {
if (j == 0 || i == 0) {
pascal = 1; //first element of pascal's triangle
}
else {
pascal = pascal *(i - j + 1) / j; //pascal's triangle formula
}
array[i][j] = pascal; //fill the array
cout << " " << pascal; // printing pascals triangle
}
cout << "\n";
}
cout << "enter which row to intergrate: ";
// here I want to directly access a row rather that entering the elements of the row
cin >> row_nb; //input the row you want to access
for (int i = 0; i <= row_nb; i++) { //access the elements in this row in the array
cout << array[row_nb][i] << " ";
}
return 0; // add the return statement since the return type of the main function is int
}

Answer 2

As I said when you last asked this :
You could simply store each row into a std::vector<int> as you calculate it (in addition to, or instead of, printing it), then keep a list of rows in a std::vector<std::vector<int>>. Then, to access the nth row after calculating the triangle, you just grab the nth element of the second vector.