Hash Table Voting System

📊 Hash Table (Size = 10)

🎯 Why Hash Table?

Problem: Prevent duplicate voting efficiently

❌ Array

O(n)

Check all voters

✅ Hash Table

O(1)

Direct check

How it works:
1️⃣ Name → Hash Function → Index
2️⃣ Search entire table for duplicate
3️⃣ If not found → Store at calculated index
4️⃣ If found → Reject duplicate

💻 Hash Table Implementation - CORRECTED

🔧 THE FIX: Check if EXACT name exists anywhere in table, not just if slot is occupied

Corrected Vote Logic

function vote(name) {
    // Step 1: Check if this EXACT name already exists ANYWHERE
    for (let i = 0; i < 10; i++) {
        if (hashTable[i] === name) {
            console.log(`❌ "${name}" already voted at index ${i}`);
            return false;
        }
    }

    // Step 2: Name not found - Calculate index and find empty slot
    let index = hashFunction(name);
    let tries = 0;

    while (tries < 10) {
        if (hashTable[index] === null) {
            // Empty slot found - Store name
            hashTable[index] = name;
            console.log(`✅ "${name}" stored at index ${index}`);
            return true;
        }
        // Slot occupied - Try next slot (linear probing)
        index = (index + 1) % 10;
        tries++;
    }

    console.log("❌ Table full");
    return false;
}

Example

// John votes
vote("John");
// Check table: "John" not found
// hash("John") = 8 → Empty → Store at 8
// ✅ ACCEPTED

// Syed votes
vote("Syed");
// Check table: "Syed" not found
// hash("Syed") = 8 → Occupied by "John"
// Try index 9 → Empty → Store at 9
// ✅ ACCEPTED (No false rejection!)

// John tries again
vote("John");
// Check table: "John" found at index 8
// ❌ REJECTED - Already voted!

🗳️ Hash Table Voting System

📊 Hash Table (Size = 10)

🎯 Why Hash Table?

💻 Hash Table Implementation - CORRECTED

Corrected Vote Logic

Example