Daily Challenges

Code Challenges

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Challenge #42

Intermediate

Implement a PDA-based Counter Program

Create a Solana program using Anchor that initializes a counter PDA and provides increment/decrement instructions. The counter should track the authority and enforce access control.

AnchorPDAAccess Control

use anchor_lang::prelude::*;

declare_id!("YourProgramId");

#[program]
pub mod counter {
    use super::*;

    pub fn initialize(ctx: Context<Initialize>) -> Result<()> {
        // TODO: Initialize the counter account
        // Set count to 0 and authority to the signer
        Ok(())
    }

    pub fn increment(ctx: Context<Update>) -> Result<()> {
        // TODO: Increment the counter
        // Only the authority should be able to increment
        Ok(())
    }

    pub fn decrement(ctx: Context<Update>) -> Result<()> {
        // TODO: Decrement the counter
        // Prevent underflow (count should not go below 0)
        Ok(())
    }
}

#[derive(Accounts)]
pub struct Initialize<'info> {
    // TODO: Define accounts for initialization
}

#[derive(Accounts)]
pub struct Update<'info> {
    // TODO: Define accounts for update
}

#[account]
pub struct Counter {
    // TODO: Define counter state
}

Test Cases

✓ Counter initializes with count = 0

✓ Authority can increment the counter

✓ Authority can decrement the counter

✗ Non-authority cannot modify the counter

✗ Counter cannot go below 0

Progressive Hints

Time Remaining

30:00

200 XP

Reward

127 attempts 43 solved