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C Program to print Pattern 6 1234321 12321 121 1

C Code Example — Pattern Programs

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C Program to print Pattern 6 1234321 12321 121 1

Objective

Write a C program to print an inverted numerical pyramid.

Algorithm / Approach

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

Expected Output

1234321
 12321
  121
   1

Explanation of the Program

  • This is the exact opposite of a standard pyramid. Instead of starting with 1 item and growing to 5, it starts with a wide base and shrinks.
  • To achieve the shrinking effect, the bounds of the inner loops must decrease as the outer loop counter (i) increases (e.g., 5 - i).

Complexity

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