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C Program to print Pattern 4 1 121 12321 1234321 123454321

C Code Example — Pattern Programs

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C Program to print Pattern 4 1 121 12321 1234321 123454321

Objective

Write a C program to print a pyramid of palindrome numbers.

Algorithm / Approach

  1. Run an outer loop i from 1 to 5.
  2. Run a first inner loop to print spaces (decreasing).
  3. Run a second inner loop j from 1 up to i, printing j (ascending numbers).
  4. Run a third inner loop starting from i - 1 down to 1, printing j (descending numbers).
  5. Print a newline.
main.c 
#include<stdio.h>
int main( ) {
 int i,j;
 for(i=1;i<=5;i++) {
  for(j=4;j>=i;j--) {
   printf(" ",j);
  }
  for(j=1;j<=i;j++) {
   printf("%d",j);
  }
  for(j--;j>=1;j--) { 
   printf("%d",j);
  }
  printf("\n");
 }
 return 0;
}

Expected Output

1
   121
  12321
 1234321
123454321

Explanation of the Program

  • This pattern creates a pyramid where each row is a numerical palindrome (e.g., 12321).
  • It is constructed using three distinct inner loops per row: one for the left padding spaces, one to count up to the peak number, and one to count back down to 1.

Complexity

Time Complexity O(n^2)
Space Complexity O(1)
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