How to Print Pascal Triangle in C++ (with Source Code)

ACMer

11 years ago

Pascal Triangle is a triangle made of numbers. The first row (root) has only 1 number which is 1, the second row has 2 numbers which again are 1 and 1. The third row has 3 numbers, which is 1, 2, 1 and so on. Each number equals to the sum of two numbers at its shoulder. The numbers at edges of triangle will be 1.

The source code in C++ is given as follows:

#include <iostream>
 
using namespace std;
 
const int N = 12;
 
long getNum(int n, int r) {
    int i;
    long p = 1;
    for(i = 1; i <= r; i++) {
        p = p * (n - i + 1) / i;
    }
    return p;
}
 
void print() {
    int n, r, t, i;
    for(n = 0; n <= N; n++) {
        for(r = 0; r <= n; r++) {
            if(r == 0) {
                for(i = 0; i <= N - n; i++) {
                    cout << " ";
                }
            } else {
                cout << " ";
            }
            cout.width(3); // three characters width
            cout << getNum(n, r);
            cout.width(1);
        }
        cout << endl;
    }
}
 
int main() {
    cout << "Pascal Triangle,  http://HelloACM.com" << endl << endl;
    print();
    return 0;
}

#include <iostream>

using namespace std;

const int N = 12;

long getNum(int n, int r) {
    int i;
    long p = 1;
    for(i = 1; i <= r; i++) {
        p = p * (n - i + 1) / i;
    }
    return p;
}

void print() {
    int n, r, t, i;
    for(n = 0; n <= N; n++) {
        for(r = 0; r <= n; r++) {
            if(r == 0) {
                for(i = 0; i <= N - n; i++) {
                    cout << " ";
                }
            } else {
                cout << " ";
            }
            cout.width(3); // three characters width
            cout << getNum(n, r);
            cout.width(1);
        }
        cout << endl;
    }
}

int main() {
    cout << "Pascal Triangle,  http://HelloACM.com" << endl << endl;
    print();
    return 0;
}

The function getNum takes two parameters, n and r which correspond to the position in the triangle.

Another posts on Pascal Triangles: Compute the Nth Row of a Pascal’s Triangle using Dynamic Programming Algorithm and Coding Exercise – Pascal Triangle II – C++ and Python Solution

Pascal Triangle Implementations:

–EOF (The Ultimate Computing & Technology Blog) —

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