SystemVerilog Testbench Introduction

SystemVerilog Testbench Architecture

APB Interface

APB Transaction

APB Generator

APB Driver

APB Driver Phase 2

APB Monitor

APB Scoreboard

APB Environment

APB Testbench Top

RISC-V Processor (YARP) Interface

YARP Transaction

YARP Generator

YARP Driver

YARP Data Memory Model

YARP Monitor

YARP Scoreboard

YARP Testbench Top

DVCon 26 Hackathon Problem

Array Sum Limit

Array Index Sum Limit

Ball Draw No Repeat

Conditional Even Probability

Even Odd Index Value

Five Consecutive Ones

Frequency Constraint

Grouped Ones

Index Value Range

Leap Year

Matrix Rotation

Non Adjacent Ones

Power of 4

Dynamic Ranges

Recent Four Unique

Row Max Unique

Subarray Max Sum

Three Duplicates Only

Tic Tac Toe

Unique 3D Array

Weighted Popcount

Unique Sum

Split Array into Queues

# Frequency Constraint

## Problem Statement

Generate an array where each distinct value appears a specific number of times. This tests understanding of counting constraints and element frequency distribution.

Your task is to write constraints to generate arrays where:
1. Element 0 appears exactly 4 times
2. Element 1 appears exactly 3 times
3. Element 2 appears exactly 2 times
4. Element 3 appears exactly 1 time
5. Elements 4 and 5 do not appear (0 times)

## Constraints
- Array size: 10 elements
- Value range: [0, 5]
- Total frequency: 4 + 3 + 2 + 1 = 10 (fills entire array)
- Use `sum(arr == value)` to count occurrences

## Examples

### Example 1:
```
Array: [0, 0, 0, 0, 1, 1, 1, 2, 2, 3]

Frequency Distribution:
  Element 0: 4 times
  Element 1: 3 times
  Element 2: 2 times
  Element 3: 1 time
  Element 4: 0 times
  Element 5: 0 times
```
Explanation: Exact frequency distribution required.

### Example 2:
```
Array: [3, 2, 2, 1, 0, 0, 1, 0, 1, 0]

Frequency Distribution:
  Element 0: 4 times
  Element 1: 3 times
  Element 2: 2 times
  Element 3: 1 time
  Element 4: 0 times
  Element 5: 0 times
```
Explanation: Same frequencies in different order.

### Example 3 (Invalid):
```
Array: [0, 0, 0, 1, 1, 1, 1, 2, 2, 3]

Frequency Distribution:
  Element 0: 3 times (expected 4)
  Element 1: 4 times (expected 3)
  Element 2: 2 times (CORRECT)
  Element 3: 1 time (CORRECT)
```
Explanation: Frequency mismatch violates constraints.

## Starter Code Pointer

The constraint demonstrates:
1. Using `sum()` with comparison operators to count occurrences
2. Aggregate frequency constraints ensuring exact counts
3. The complementary constraint system (all frequencies must sum to array size)
