🟢 Beginner · Lesson 16

Pattern Programs

Understanding Pattern Programs

Pattern programs are a classic way to practice nested loops. The key insight is:

Outer loop → controls the number of rows
Inner loop → controls the number of columns (characters per row)
The relationship between the row number and column count determines the shape

💡 Strategy to Solve Any Pattern

Look at the pattern — how many rows?
In each row, what's printed and how many times?
Find the relationship between row number (i) and column count (j)
Write outer loop for rows, inner loop(s) for columns

Star Patterns

Pattern 1: Right Triangle (Increasing)

C Language

#include <stdio.h>
int main() {
    int n = 5;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= i; j++)   // j goes from 1 to i
            printf("* ");
        printf("\n");
    }
    return 0;
}

* * * * * * * * * * * * * * *

Pattern 2: Inverted Right Triangle

C Language

int n = 5;
for (int i = n; i >= 1; i--) {     // i starts from n, counts down
    for (int j = 1; j <= i; j++)
        printf("* ");
    printf("\n");
}

* * * * * * * * * * * * * * *

Pattern 3: Square Pattern

C Language

int n = 4;
for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++)   // Always n columns
        printf("* ");
    printf("\n");
}

* * * * * * * * * * * * * * * *

Pattern 4: Hollow Rectangle

C Language

int rows = 4, cols = 6;
for (int i = 1; i <= rows; i++) {
    for (int j = 1; j <= cols; j++) {
        if (i == 1 || i == rows || j == 1 || j == cols)
            printf("* ");   // Border only
        else
            printf("  ");   // Interior spaces
    }
    printf("\n");
}

* * * * * * * * * * * * * * * *

Number Patterns

Pattern 5: Floyd's Triangle

C Language

int n = 5, num = 1;
for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= i; j++)
        printf("%3d", num++);   // num increases continuously
    printf("\n");
}

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Pattern 6: Number Triangle (1 to i)

C Language

for (int i = 1; i <= 5; i++) {
    for (int j = 1; j <= i; j++)
        printf("%d ", j);
    printf("\n");
}

1 1 2 1 2 3 1 2 3 4 1 2 3 4 5

Pattern 7: Same Number Each Row

C Language

for (int i = 1; i <= 5; i++) {
    for (int j = 1; j <= i; j++)
        printf("%d ", i);   // Print row number i times
    printf("\n");
}

1 2 2 3 3 3 4 4 4 4 5 5 5 5 5

Alphabet Patterns

Pattern 8: Alphabet Triangle

C Language

for (int i = 1; i <= 5; i++) {
    for (int j = 0; j < i; j++)
        printf("%c ", (char)('A' + j));  // A B C D E
    printf("\n");
}

A A B A B C A B C D A B C D E

Pyramid Patterns (Centered)

Pattern 9: Centered Star Pyramid

C Language

#include <stdio.h>
int main() {
    int n = 5;
    for (int i = 1; i <= n; i++) {
        for (int s = 1; s <= n - i; s++)   // Leading spaces
            printf(" ");
        for (int j = 1; j <= 2*i - 1; j++)  // Stars: 2i-1
            printf("*");
        printf("\n");
    }
    return 0;
}

* *** ***** ******* *********

Pattern 10: Diamond Pattern

C Language

#include <stdio.h>
int main() {
    int n = 4;
    // Upper half
    for (int i = 1; i <= n; i++) {
        for (int s = 1; s <= n - i; s++) printf(" ");
        for (int j = 1; j <= 2*i - 1; j++) printf("*");
        printf("\n");
    }
    // Lower half
    for (int i = n - 1; i >= 1; i--) {
        for (int s = 1; s <= n - i; s++) printf(" ");
        for (int j = 1; j <= 2*i - 1; j++) printf("*");
        printf("\n");
    }
    return 0;
}

* *** ***** ******* ***** *** *

Practice Summary

You've learned 10 patterns. Try these on your own:

#	Pattern Name	Technique
1	Right Triangle ★	j from 1 to i
2	Inverted Triangle ★	i from n down to 1
3	Square ★	j always from 1 to n
4	Hollow Rectangle ★★	border condition
5	Floyd's Triangle ★★	continuous counter num++
6	Number 1-to-i ★	print j
7	Same Number Each Row ★	print i
8	Alphabet Triangle ★★	'A' + j
9	Centered Pyramid ★★	spaces + 2i-1 stars
10	Diamond ★★★	pyramid + inverted

🏋️ More Practice Patterns

Try: (1) Right-aligned triangle (spaces on left) (2) Pascal's triangle (3) Butterfly pattern (4) X pattern (5) Checkerboard pattern (alternating * and space)

Patterns समझना

Pattern programs nested loops practice का classic तरीका है। Key insight:

Outer loop → rows की संख्या control करता है
Inner loop → columns की संख्या (हर row में characters) control करता है
Row number (i) और column count (j) का relationship shape determine करता है

💡 हर Pattern Solve करने की Strategy

Pattern देखो — कितने rows हैं?
हर row में क्या print होता है और कितनी बार?
Row number (i) और column count (j) का relation ढूंढो
Rows के लिए outer loop, columns के लिए inner loop लिखो

Star Patterns

Pattern 1: Right Triangle

C Language

int n = 5;
for(int i=1; i<=n; i++) {
    for(int j=1; j<=i; j++) printf("* "); // j, 1 से i तक
    printf("\n");
}

* * * * * * * * * * * * * * *

Pattern 2: Inverted Triangle

C Language

for(int i=5; i>=1; i--) {    // i n से शुरू, नीचे जाता है
    for(int j=1; j<=i; j++) printf("* ");
    printf("\n");
}

* * * * * * * * * * * * * * *

Number Patterns

Pattern 3: Floyd's Triangle

C Language

int num = 1;
for(int i=1; i<=5; i++) {
    for(int j=1; j<=i; j++) printf("%3d", num++);
    printf("\n");
}

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Pattern 4: Ek Row mein Same Number

C Language

for(int i=1; i<=5; i++) {
    for(int j=1; j<=i; j++) printf("%d ", i); // row number i print
    printf("\n");
}

1 2 2 3 3 3 4 4 4 4 5 5 5 5 5

Pyramid Pattern (Centered)

C Language – Star Pyramid

int n = 5;
for(int i=1; i<=n; i++) {
    for(int s=1; s<=n-i; s++) printf(" ");   // Spaces
    for(int j=1; j<=2*i-1; j++) printf("*"); // Stars: 2i-1
    printf("\n");
}

* *** ***** ******* *********

Practice Summary

#	Pattern	Technique
1	Right Triangle	j, 1 से i तक
2	Inverted Triangle	i, n से 1 तक
3	Floyd's Triangle	continuous counter num++
4	Same Number	i print करो i बार
5	Centered Pyramid	spaces + 2i-1 stars

🏋️ और Practice Patterns

Try करें: (1) Right-aligned triangle (left side spaces) (2) Pascal's triangle (3) Diamond pattern (4) Hollow triangle (5) Checkerboard (* और space alternate)

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