Left-Shifted Odd Number Triangle in C

What You’ll Learn

The left-shifted odd number triangle prints consecutive odd digits on each row while the starting odd value increases — a great exercise in nested loops with step size 2. 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 max, print a left-shifted odd number triangle: row starting at odd i prints odd digits from i to max stepping by 2.

// max = 10 (conceptual shape)
// 13579
// 3579
// 579
// 79
// 9

Inputs & Outputs

Minimal workflow

for i from 1 to max step 2:
    for j from i to max step 2:
        print j (no newline)
    print newline

Approach comparison

🔮 Live Preview

Choose a maximum between 1 and 20 and draw the left-shifted odd triangle in the browser.

Press "Draw pattern".

Examples Gallery

Three complete C programs — fixed maximum, user input, and an even-number mirror variant. Click View Output to reveal sample console results.

#include <stdio.h>

int main() {
    int i, j;

    for (i = 1; i <= 10; i += 2) {
        for (j = i; j <= 10; j += 2) {
            printf("%d", j);
        }
        printf("\n");
    }

    return 0;
}

13579
3579
579
79
9

#include <stdio.h>

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

    printf("Enter the maximum value: ");
    scanf("%d", &max);

    if (max % 2 == 0) max -= 1;

    for (i = 1; i <= max; i += 2) {
        for (j = i; j <= max; j += 2) {
            printf("%d", j);
        }
        printf("\n");
    }

    return 0;
}

Enter the maximum value: 8
1357
357
57
7

#include <stdio.h>

int main() {
    int max = 10;
    int i, j;

    for (i = 2; i <= max; i += 2) {
        for (j = i; j <= max; j += 2) {
            printf("%d", j);
        }
        printf("\n");
    }

    return 0;
}

246810
46810
6810
810
10

🔎 Worked Walkthrough — max = 10

Trace each outer-loop value of i and note the odd j values printed on each row.

Five rows for max = 10; digit count shrinks from 5 down to 1.

🎯 Practice Problems

Try these variations to lock in the pattern.

Notes

⏱️ Time and Space Complexity

💡 Best Practices