Descending Repeating Number Triangle in C++

What You’ll Learn

The descending repeating number triangle flips Program 9’s outer loop: digit decreases each row while repeats increase — nested loops, cout vs newline, and a clear visual result. This tutorial covers the shape rule, loop structure, a live preview, algorithm steps, worked C++ examples, edge cases, and complexity.

📝 Problem & Approach

Given a positive integer rows, print a descending repeating number triangle: row i repeats digit i exactly rows - i + 1 times, with the outer loop counting from rows down to 1.

// First 5 rows (conceptual shape)
// 5
// 44
// 333
// 2222
// 11111

Inputs & Outputs

Minimal workflow

for i from rows down to 1:
    repeat (rows - i + 1) times:
        print i (no newline)
    print newline

Approach comparison

🔮 Live Preview

Choose a row count between 1 and 20 and draw the descending repeating number triangle in the browser.

Press "Draw pattern".

Examples Gallery

Three complete C++ programs — fixed row count, cin input, and a string row shortcut. Click View Output to reveal sample console results.

#include <iostream>
using namespace std;

int main() {
    int rows = 5;
    int i, j;

    for (i = rows; i >= 1; --i) {
        for (j = rows; j >= i; --j) {
            cout << i;
        }
        cout << "\n";
    }

    return 0;
}

5
44
333
2222
11111

#include <iostream>
using namespace std;

int main() {
    int rows;
    int i, j;

    cout << "Enter the number of rows: ";
    cin >> rows;

    for (i = rows; i >= 1; --i) {
        for (j = rows; j >= i; --j) {
            cout << i;
        }
        cout << "\n";
    }

    return 0;
}

Enter the number of rows: 4
4
33
222
1111

#include <iostream>
#include <string>
using namespace std;

int main() {
    int rows = 5;

    for (int i = rows; i >= 1; --i) {
        cout << string(rows - i + 1, char('0' + i)) << "\n";
    }

    return 0;
}

5
44
333
2222
11111

🔎 Worked Walkthrough — rows = 4

Trace each outer-loop value of i and count how many times the inner loop prints digit i.

Total digit prints: 1 + 2 + 3 + 4 = 10 = 4×5/2.

🎯 Practice Problems

Try these variations to lock in the pattern.

Notes

⏱️ Time and Space Complexity

💡 Best Practices