Pascal's Triangle in C++ With Examples

Named after the French mathematician, Blaise Pascal, the Pascal’s Triangle is a triangular structure of numbers. The triangle is constructed using a simple additive principle, explained in the following figure.

pascal_triangle_principle_edited

Principle of Pascal’s Triangle

Each entry, except the boundary of ones, is formed by adding the above adjacent elements. Even though the formation of Pascal’s triangle is simple, it holds a huge number of mathematical properties and applications.

Properties of Pascal’s Triangle

Let us go through some mind-blowing properties of Pascal’s Triangle.

Combinations

Any high-school student with mathematical background must have gone through the course of Permutations and Combinations. The combinations section refers to the number of ways we can choose certain objects from a group of objects.

Combinations formula

Using the row and the column number, each value can be replaced as follows:

Pascal’s Triangle as Combinations

This property further extends to the binomial expansions, where each binomial coefficient represents the value of the Pascal’s Triangle.


Hockey Stick Identity

A very unique property of Pascal’s triangle is – “At any point along the diagonal, the sum of values starting from the border, equals to the value in the next row, in the opposite direction of the diagonal.”

Hockey Stick Identity

It is quite clear from the figure that, the separate sums form individual hockey sticks.


Fibonacci Numbers

The Pascal’s Triangle is related to many sequences like Fibonacci Numbers, Catalan Numbers, Triangular Numbers, etc. To obtain the Fibonacci numbers, we first need to indent the numbers to the left side and then add up numbers along the diagonal.

pascal_triangle_hockey_edited

Pascal’s triangle with Fibonacci numbers

There are too many stunning concepts related to Pascal’s triangle to cover in this article. Curious readers can search for topics like Sierpinski’s triangle and Lozanic’s Triangle, and their connection with Pascal’s triangle.


Efficient Implementation of Pascal’s Triangle in C++

Output:


The insight behind the implementation

The logic for the implementation given above comes from the Combinations property of Pascal’s Triangle. We know that each value in Pascal’s triangle denotes a corresponding nCr value.

Each successive combination value can be calculated using the equation below.

Relation with successive combination values

In the inner loop of the above code, the 'val' variable keeps updating with every successive combination value.


Conclusion

At first, Pascal’s Triangle may look like any trivial numerical pattern, but only when we examine its properties, we can find amazing results and applications.

We hope this article was as interesting as Pascal’s Triangle. Feel free to comment below for any queries or feedback.

Read further: Trie Data Structure in C++

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One thought on “Pascal’s Triangle in C++ With Examples [Latest]”
  1. Thanks for sharing your knoledge with us. I worte a pascal’s triangle code in c++ using ur logic. problem is- it doesnt look like tringangle anymore after column 5 is printed. Meaning-if i enter col=6 it gets a trrible shape after column 5.

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