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cloopsfor-loopwhile-loop
Naru
Naru

Reputation: 29

How to draw the Pascal's Triangle using C language?

I'm trying to write code that prints the following :

Pascal Triangle

Here's what I have tried :

#include <stdio.h>

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

    printf("Enter number of rows: ");
    scanf("%d", &rows);

    for (i = rows; i >= 0; i--) {

        for (j = 1; j <= i; ++j) {
            printf("* ");
        }

        printf("\n");
    }

    return 0;
}

How do I do this ?

Upvotes: 1

Views: 598

Answers (1)

chqrlie
chqrlie

Reputation: 144740

Here is a simple example:

#include <stdio.h>

int main() {
    int rows, i, j, w;

    printf("Enter number of rows: ");
    if (scanf("%d", &rows) != 1)   // get the number of rows, exit if input error
        return 1;

    int coeff[rows + 1];           // array to store the binomial coefficients
    for (i = 0; i < rows; i++) {
        coeff[i] = 1;              // initialize the last coefficient to 1
        for (j = i - 1; j > 0; j--) {
            coeff[j] += coeff[j - 1];  // add adjacent coefficients to get the new value
        }
        w = (rows - i) * 3;        // output 3 extra leading spaces for each row from the end
        for (j = 0; j <= i; j++) { // output i+1 coefficients
            printf(" %*d", w, coeff[j]);
            w = 5;                 // output more coefficients on 1+5 characters
        }
        printf("\n");
    }
    return 0;
}

Output:

Enter number of rows: 6
                  1
               1     1
            1     2     1
         1     3     3     1
      1     4     6     4     1
   1     5    10    10     5     1

Upvotes: 5

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