C++ Program to print the diamond shape

In this article, we will learn how to print a diamond shape with 2n rows and n columns for a given size n using C++.

For example, if n = 4, the diamond shape will look like this:

Algorithm to Print Diamond Shape

To print the diamond shape, we can follow these steps:

• Take an integer input n from the user.
• To print upper half of the diamond, use a loop that runs from i = 1 to i <= n.
• In each iteration of the loop, print empty spaces from j = 1 to j = n - i
• Then, print stars from j = 1 to j <= i.
• After printing the stars of each row, print a newline character to move to the next line.
• Now, to print the lower half of the diamond, use a loop that runs from i = n to i >= 1.
• Use the same code as above to print empty spaces and stars for the lower half.

C++ Program to Print Diamond Shape

The C++ code below, implements the above algorithm to print a diamond shape. This consist of two separate nested loops for the upper and lower halves of the diamond.

#include <iostream>
using namespace std;

int main() {
    int n = 6;  // Height of the upper half
    cout << "Diamond Shape of " << 2*n << " Rows and " << n << " Columns:" << endl;
    cout << "----------------------------------------" << endl;

    // Upper half of the diamond
    for (int i = 1; i <= n; ++i) {
        // Print spaces
        for (int j = 1; j <= n - i; ++j)
            cout << " ";

        // Print stars
        for (int j = 1; j <= i; ++j)
            cout << "* ";

        cout << endl;
    }

    // Lower half of the diamond
    for (int i = n; i >= 1; --i) {
        // Print spaces
        for (int j = 1; j <= n - i; ++j)
            cout << " ";

        // Print stars
        for (int j = 1; j <= i; ++j)
            cout << "* ";

        cout << endl;
    }

    return 0;
}

The output of the above code will be:

Time and Space Complexity

Time Complexity: The time complexity of this algorithm is O(n^2), where n is the number of rows in the upper half of the diamond.

Space Complexity: The space complexity is O(1) since we are not storing any data in program.