Right Arrow Pattern Program In Python

Print an arrow pattern using hyphens and asterisks based on an odd integer N

Understand the Problem

Problem Statement

The program must accept an odd integer N as the input. The program must print N lines containing hyphens and asterisks based on the following conditions:

In the line 1, the program must print (N-1)/2 hyphens followed by an asterisk.
In the line 2, the program must print (N-1)/2 + 1 hyphens followed by an asterisk.
In the line 3, the program must print (N-1)/2 + 2 hyphens followed by an asterisk.
Similarly, the program must print the first (N-1)/2 lines as the output.
In the line (N+1)/2, the program must print N asterisks.
In the line (N+1)/2 + 1, the program must print N-2 hyphens followed by an asterisk.
In the line (N+1)/2 + 2, the program must print N-3 hyphens followed by an asterisk.
In the line (N+1)/2 + 3, the program must print N-4 hyphens followed by an asterisk.
Similarly, the program must print the remaining lines as the output.

Constraints

5 <= N <= 99
N must be an odd integer
Each line consists only of hyphens (-) and asterisks (*)
The pattern forms a right-facing arrow shape

Examples

Example 1

Input

Output

--*
---*
*****
---*
--*

Explanation

For N=5, the pattern has: - Line 1: (5-1)/2 = 2 hyphens + 1 asterisk = '--*' - Line 2: 2+1 = 3 hyphens + 1 asterisk = '---*' - Line 3: 5 asterisks = '*****' - Line 4: 5-2 = 3 hyphens + 1 asterisk = '---*' - Line 5: 5-3 = 2 hyphens + 1 asterisk = '--*'

Example 2

Input

Output

---*
----*
-----*
*******
-----*
----*
---*

Explanation

For N=7, the pattern has: - Lines 1-3: Increasing hyphens (3, 4, 5) followed by asterisk - Line 4: 7 asterisks forming the arrow's center - Lines 5-7: Decreasing hyphens (5, 4, 3) followed by asterisk

Solution

#include <stdio.h>

int main() {
    int N;
    scanf("%d", &N);
    
    int mid = (N + 1) / 2;
    int spaces;
    
    // Upper half of the arrow
    for (int i = 1; i < mid; i++) {
        spaces = (N - 1) / 2 + (i - 1);
        for (int j = 0; j < spaces; j++) {
            printf("-");
        }
        printf("*");
        printf("\n");
    }
    
    // Center line (full width)
    for (int i = 0; i < N; i++) {
        printf("*");
    }
    printf("\n");
    
    // Lower half of the arrow
    for (int i = mid + 1; i <= N; i++) {
        spaces = N - (i - mid) - 1;
        for (int j = 0; j < spaces; j++) {
            printf("-");
        }
        printf("*");
        printf("\n");
    }
    
    return 0;
}

Time:O(N²) - The nested loops for printing hyphens make it quadratic in terms of N

Space:O(1) - Only using a constant amount of extra space for variables

Approach:

Step 1: Read the odd integer N from standard input.

Step 2: Calculate the middle line index as (N+1)/2.

Step 3: Generate the upper half by iterating from 1 to mid-1. For each line i, print (N-1)/2 + (i-1) hyphens followed by an asterisk.

Step 4: Print the center line with N asterisks.

Step 5: Generate the lower half by iterating from mid+1 to N. For each line i, print N-(i-mid)-1 hyphens followed by an asterisk.

Step 6: Each line ends with a newline character.

Visual Explanation

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