Logic to print the given number pattern 
    1
   21
  321
 4321
54321

C Programming Language Loop control in C Language (Article) Loop control in C Language (Program)

5519

Program:

/**
 * C program to print number pattern
 */

#include <stdio.h>

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

    printf("Enter N: ");
    scanf("%d", &N);

    for(i=1; i<=N; i++)
    {
        // Logic to print spaces
        for(j=1; j<=N-i; j++)
        {
            printf(" ");
        }

        // Logic to print numbers
        for(j=i; j>=1; j--)
        {
            printf("%d", j);
        }

        printf("\n");
    }

    return 0;
}

Output:

    1
   21
  321
 4321
54321

Explanation:

Logic to print the given number pattern

    1
   21
  321
 4321
54321

Logic of the above pattern is simple and similar to the previous number pattern that we just printed. In this pattern we only need to add logic of printing extra trailing spaces before the number gets printed. You can hover on to the pattern to see or count total spaces printed per row. The total number of spaces printed per row is N - i (where N is the total number of rows to be printed and i is the current row number).
Step-by-step descriptive logic of the printing spaces:

  1. To print spaces, run an inner loop from 1 to N - i. Inside this loop print single blank space.

Finally you are done, lets now implement this on code.

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