C++ Code to Print Pascal Triangle

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Printing Pascal Triangle seems like an easy problem, however, it is not that easy to print a good-looking Pascal Triangle.

To print the Pascal Triangle, for each line, first print spaces to the left of numbers, and then print digit numbers.

To calculate Pascal numbers, two assays can be used: one array to store numbers of above line, the other array to store numbers of this line. The first line has 1 number(1), the second lien has 2 numbers(1 1), the third line has three numbers(1 2 1) and so on.

To make the Pascal Triangle more readable, print spaces between two neighbor numbers in the same line.

// Pascal triangle#include <iostream>#include <iomanip>#include <cstring>using namespace std;const int WIDTH=7;int main(){int* oldarr=new int[WIDTH]; // store numbers of above rowint* newarr=new int[WIDTH]; // store numbers of current rowfor(int i=0;i<WIDTH;++i) // cntrol row counting{for(int j=0;j<WIDTH-i-1;++j) // left spacecout<<setw(2)<<" ";// set default boundary numbersnewarr[0]=1;if(i>=1)newarr[i]=1;if(i>=2){for(int k=1;k<i;++k)newarr[k]=oldarr[k-1]+oldarr[k];}memcpy(oldarr,newarr,sizeof(int)*WIDTH);// Print the middle partint idx=0;int flag=(WIDTH-i-1)%2;for(int j=WIDTH-i-1;j<WIDTH+i;++j){if(j%2==flag){cout<<setw(2)<<newarr[idx++];} else {cout<<setw(2)<<" ";}}//for(int j=WIDTH+i;j<WIDTH;++j) // Print right space, if you like//cout<<setw(4)<<" ";cout<<endl;}delete [] oldarr;delete [] newarr;return 0;}

The output looks like:

             1           1   1         1   2   1       1   3   3   1     1   4   6   4   1   1   5  10  10   5   1 1   6  15  20  15   6   1

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