algorithm-neet-code-top-150-python-visual/visual/0217_contains_duplicate.html at main · kimtth/algorithm-neet-code-top-150-python-visual · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>LC 217: Contains Duplicate - Algorithm Visualization</title>
    <link rel="stylesheet" href="styles.css">
    <script src="https://d3js.org/d3.v7.min.js"></script>
</head>
<body>
    <div class="container">
        <div class="problem-info">
            <h1><span class="problem-number">#217</span> Contains Duplicate</h1>
            <p>Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.</p>
            <div class="problem-meta">
                <span class="meta-tag">📁 Array</span>
                <span class="meta-tag">🔤 Hash Set</span>
                <span class="meta-tag">⏱️ O(n)</span>
                <span class="meta-tag">💾 O(n)</span>
            </div>
            <div class="file-ref">
                📄 Python: <code>python/0217_contains_duplicate/0217_contains_duplicate.py</code>
            </div>
            </div>

        <div class="explanation-panel">
            <h4>🧠 How It Works (Layman's Terms)</h4>
            <p>Think of it like checking names at a party entrance:</p>
            <ul>
                <li>You have a guest list (empty set at first)</li>
                <li>As each person arrives, you check: "Have I seen this person before?"</li>
                <li>If <strong>YES</strong> → Duplicate found! Return true</li>
                <li>If <strong>NO</strong> → Add their name to the list and continue</li>
                <li>If everyone enters without a repeat → No duplicates, return false</li>
            </ul>
            <p>The <strong>set</strong> provides O(1) lookup, making this very efficient!</p>
        </div>


        <div class="visualization-section">
            <h3>🎬 Step-by-Step Visualization</h3>

            <div class="controls">
                <button class="btn btn-primary" id="stepBtn" onclick="step()">Step</button>
                <button class="btn btn-success" id="autoBtn" onclick="toggleAuto()">Auto Run</button>
                <button class="btn btn-warning" onclick="reset()">Reset</button>
            </div>

            <div class="status-message" id="statusMessage">
                Click "Step" or "Auto Run" to start visualization
            </div>

            <div class="array-section">
                <div class="array-label">📥 Input Array:</div>
                <div class="array-container" id="inputContainer"></div>
            </div>

            <div class="array-section">
                <div class="array-label">👁️ Seen Set (Hash Set):</div>
                <div class="array-container" id="seenContainer">
                    <div style="color: #999; padding: 10px;">{ empty }</div>
                </div>
            </div>

            <div class="info-box" id="resultBox" style="display: none;">
                Result will appear here
            </div>
        </div>
        <div class="code-section">
            <h3>💻 Python Solution</h3>
            <div class="code-block">
                <pre>from typing import List


"""
LeetCode 217: Contains Duplicate

Problem from LeetCode: https://leetcode.com/problems/contains-duplicate/

Given an integer array nums, return true if any value appears at least twice in the array,
and return false if every element is distinct.

Example 1:
Input: nums = [1,2,3,1]
Output: true

Example 2:
Input: nums = [1,2,3,4]
Output: false

Example 3:
Input: nums = [1,1,1,3,3,4,3,2,4,2]
Output: true

Constraints:
- 1 &lt;= nums.length &lt;= 10^5
- -10^9 &lt;= nums[i] &lt;= 10^9
"""

class Solution:

    def contains_duplicate(self, nums: List[int]) -&gt;bool:
        """
        Determine if the array contains any duplicates.

        Args:
            nums: An array of integers

        Returns:
            bool: True if any value appears at least twice in the array, False otherwise
        """
        seen = set()
        for num in nums:
            if num in seen:
                return True
            seen.add(num)
        return False

    def contains_duplicate_alternative(self, nums: List[int]) -&gt;bool:
        """
        Alternative implementation using set comparison.

        Args:
            nums: An array of integers

        Returns:
            bool: True if any value appears at least twice in the array, False otherwise
        """
        return len(set(nums)) &lt; len(nums)

if __name__ == '__main__':
    # Example usage based on LeetCode sample
    solution = Solution()

    # Example 1
    nums = [1, 2, 3, 1]
    result = solution.contains_duplicate(nums)
    print(result)  # Output: True

    # Example 2
    nums = [1, 2, 3, 4]
    result = solution.contains_duplicate(nums)
    print(result)  # Output: False

    # Example 3
    nums = [1, 1, 1, 3, 3, 4, 3, 2, 4, 2]
    result = solution.contains_duplicate(nums)
    print(result)  # Output: True
</pre>
            </div>
        </div>
    </div>

    <script>
        const nums = [1, 2, 3, 1];
        let seen = new Set();
        let currentIndex = 0;
        let foundDuplicate = false;
        let autoInterval = null;

        function init() {
            renderInput();
            renderSeen();
        }

        function renderInput() {
            const container = document.getElementById('inputContainer');
            container.innerHTML = '';
            nums.forEach((num, idx) => {
                const box = document.createElement('div');
                box.className = 'array-box';
                box.id = `input-${idx}`;
                box.innerHTML = `${num}<span class="index-label">[${idx}]</span>`;
                container.appendChild(box);
            });
        }

        function renderSeen() {
            const container = document.getElementById('seenContainer');
            container.innerHTML = '';

            if (seen.size === 0) {
                container.innerHTML = '<div style="color: #999; padding: 10px;">{ empty }</div>';
                return;
            }

            const setValues = Array.from(seen);
            setValues.forEach(val => {
                const box = document.createElement('div');
                box.className = 'array-box';
                box.id = `seen-${val}`;
                box.style.background = '#e8f5e9';
                box.style.borderColor = '#4caf50';
                box.textContent = val;
                container.appendChild(box);
            });
        }

        function step() {
            if (foundDuplicate || currentIndex >= nums.length) {
                document.getElementById('stepBtn').disabled = true;
                stopAuto();
                return;
            }

            // Clear previous highlights
            document.querySelectorAll('.array-box').forEach(box => {
                box.classList.remove('highlight', 'current');
            });

            const currentNum = nums[currentIndex];
            document.getElementById(`input-${currentIndex}`).classList.add('highlight');

            if (seen.has(currentNum)) {
                // Found duplicate!
                foundDuplicate = true;
                document.getElementById('statusMessage').className = 'status-message warning';
                document.getElementById('statusMessage').textContent =
                    `🚨 Checking ${currentNum}: Already in set! DUPLICATE FOUND!`;

                // Highlight the duplicate in the seen set
                if (document.getElementById(`seen-${currentNum}`)) {
                    document.getElementById(`seen-${currentNum}`).classList.add('highlight');
                    document.getElementById(`seen-${currentNum}`).style.background = '#ffcdd2';
                    document.getElementById(`seen-${currentNum}`).style.borderColor = '#f44336';
                }
                document.getElementById(`input-${currentIndex}`).style.background = '#ffcdd2';
                document.getElementById(`input-${currentIndex}`).style.borderColor = '#f44336';

                const resultBox = document.getElementById('resultBox');
                resultBox.style.display = 'block';
                resultBox.className = 'info-box highlight';
                resultBox.textContent = '✅ Return TRUE - Duplicate exists!';

                document.getElementById('stepBtn').disabled = true;
                stopAuto();
            } else {
                // Add to set
                seen.add(currentNum);
                document.getElementById('statusMessage').textContent =
                    `Checking ${currentNum}: Not in set → Adding to seen set`;
                renderSeen();

                currentIndex++;

                if (currentIndex >= nums.length && !foundDuplicate) {
                    document.getElementById('statusMessage').className = 'status-message success';
                    document.getElementById('statusMessage').textContent =
                        '✅ Checked all elements. No duplicates found!';

                    const resultBox = document.getElementById('resultBox');
                    resultBox.style.display = 'block';
                    resultBox.className = 'info-box secondary';
                    resultBox.textContent = '❌ Return FALSE - All elements are unique!';

                    document.getElementById('stepBtn').disabled = true;
                    stopAuto();
                }
            }
        }

        function toggleAuto() {
            if (autoInterval) {
                stopAuto();
            } else {
                document.getElementById('autoBtn').textContent = 'Pause';
                autoInterval = setInterval(() => {
                    if (foundDuplicate || currentIndex >= nums.length) {
                        stopAuto();
                    } else {
                        step();
                    }
                }, 1000);
            }
        }

        function stopAuto() {
            if (autoInterval) {
                clearInterval(autoInterval);
                autoInterval = null;
            }
            document.getElementById('autoBtn').textContent = 'Auto Run';
        }

        function reset() {
            stopAuto();
            currentIndex = 0;
            seen = new Set();
            foundDuplicate = false;
            document.getElementById('stepBtn').disabled = false;
            document.getElementById('statusMessage').className = 'status-message';
            document.getElementById('statusMessage').textContent = 'Click "Step" or "Auto Run" to start visualization';
            document.getElementById('resultBox').style.display = 'none';
            init();
        }

        init();
    </script>
</body>
</html>