algorithm-neet-code-top-150-python-visual/visual/0567_permutation_in_string.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>Permutation in String - LeetCode 567</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">#567</span> Permutation in String</h1>
            <p>Check if s2 contains any permutation of s1 as a substring. Use a sliding window with character frequency matching!</p>
            <div class="problem-meta">
                <span class="meta-tag">🪟 Sliding Window</span>
                <span class="meta-tag">🔤 String</span>
                <span class="meta-tag">⏱️ O(n)</span>
            </div>
            <div class="file-ref">
                📄 Python: <a href="../python/0567_permutation_in_string/0567_permutation_in_string.py">0567_permutation_in_string.py</a>
            </div>
            </div>

        <div class="explanation-panel">
            <h4>💡 How It Works (Layman's Terms)</h4>
            <ul>
                <li><strong>Permutation:</strong> Same characters in any order (e.g., "ab" and "ba" are permutations)</li>
                <li><strong>Key insight:</strong> Two strings are permutations if they have the same character frequencies</li>
                <li><strong>Window size:</strong> Always equals len(s1) - a permutation must have the same length</li>
                <li><strong>Slide window:</strong> Move window one character at a time, updating frequencies</li>
                <li><strong>Match found:</strong> When window's char frequencies equal s1's frequencies</li>
            </ul>
        </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 check if s2 contains a permutation of s1
            </div>

            <div class="array-section">
                <div class="array-label">s1 (pattern to find permutation of):</div>
                <div class="array-container" id="s1Container"></div>
            </div>

            <div class="array-section">
                <div class="array-label">s2 (search in this string):</div>
                <div class="array-container" id="s2Container"></div>
            </div>

            <div style="display: flex; gap: 30px; margin-top: 20px;">
                <div class="array-section" style="flex: 1;">
                    <div class="array-label">s1 Character Counts:</div>
                    <div id="s1CountContainer" style="display: flex; gap: 10px; flex-wrap: wrap;"></div>
                </div>
                <div class="array-section" style="flex: 1;">
                    <div class="array-label">Current Window Counts:</div>
                    <div id="windowCountContainer" style="display: flex; gap: 10px; flex-wrap: wrap;"></div>
                </div>
            </div>

            <div class="info-box" id="matchBox" style="display: none;"></div>
        </div>
        <div class="code-section">
            <h3>💻 Python Solution</h3>
            <div class="code-block">
                <pre><span class="keyword">def</span> <span class="function">checkInclusion</span>(self, s1: <span class="class-name">str</span>, s2: <span class="class-name">str</span>) -> bool:
    <span class="keyword">if</span> <span class="function">len</span>(s1) > <span class="function">len</span>(s2):
        <span class="keyword">return</span> <span class="keyword">False</span>

    s1_count = <span class="function">Counter</span>(s1)
    window = <span class="function">Counter</span>(s2[:<span class="function">len</span>(s1)])

    <span class="keyword">if</span> window == s1_count:
        <span class="keyword">return</span> <span class="keyword">True</span>

    <span class="keyword">for</span> i <span class="keyword">in</span> <span class="function">range</span>(<span class="function">len</span>(s2) - <span class="function">len</span>(s1)):
        <span class="comment"># Remove leftmost char, add next char</span>
        window[s2[i]] -= <span class="number">1</span>
        <span class="keyword">if</span> window[s2[i]] == <span class="number">0</span>:
            del window[s2[i]]
        window[s2[i + <span class="function">len</span>(s1)]] += <span class="number">1</span>

        <span class="keyword">if</span> window == s1_count:
            <span class="keyword">return</span> <span class="keyword">True</span>

    <span class="keyword">return</span> <span class="keyword">False</span></pre>
            </div>
        </div>

        </div>

    <script>
        const s1 = "ab";
        const s2 = "eidbaooo";
        const windowSize = s1.length;

        let s1Count = {};
        let windowCount = {};
        let windowStart = 0;
        let phase = 'init';
        let autoInterval = null;

        function getCount(str) {
            const count = {};
            for (const c of str) {
                count[c] = (count[c] || 0) + 1;
            }
            return count;
        }

        function countsMatch(c1, c2) {
            const keys1 = Object.keys(c1).filter(k => c1[k] > 0);
            const keys2 = Object.keys(c2).filter(k => c2[k] > 0);
            if (keys1.length !== keys2.length) return false;
            for (const k of keys1) {
                if (c1[k] !== c2[k]) return false;
            }
            return true;
        }

        function init() {
            s1Count = getCount(s1);
            windowCount = {};
            windowStart = 0;
            renderS1();
            renderS2();
            renderCounts();
            document.getElementById('matchBox').style.display = 'none';
        }

        function renderS1() {
            const container = document.getElementById('s1Container');
            container.innerHTML = '';
            s1.split('').forEach((char, idx) => {
                const box = document.createElement('div');
                box.className = 'array-box';
                box.style.width = '45px';
                box.innerHTML = `${char}<span class="index-label">[${idx}]</span>`;
                container.appendChild(box);
            });
        }

        function renderS2() {
            const container = document.getElementById('s2Container');
            container.innerHTML = '';
            s2.split('').forEach((char, idx) => {
                const box = document.createElement('div');
                box.className = 'array-box';
                box.id = `s2-${idx}`;
                box.style.width = '45px';
                if (idx >= windowStart && idx < windowStart + windowSize) {
                    box.classList.add('current');
                }
                box.innerHTML = `${char}<span class="index-label">[${idx}]</span>`;
                container.appendChild(box);
            });
        }

        function renderCounts() {
            const s1Container = document.getElementById('s1CountContainer');
            s1Container.innerHTML = '';
            Object.entries(s1Count).sort().forEach(([char, count]) => {
                const box = document.createElement('div');
                box.className = 'variable-box';
                box.innerHTML = `<div class="variable-name">'${char}'</div><div class="variable-value">${count}</div>`;
                s1Container.appendChild(box);
            });

            const windowContainer = document.getElementById('windowCountContainer');
            windowContainer.innerHTML = '';
            const windowKeys = Object.keys(windowCount).filter(k => windowCount[k] > 0).sort();
            if (windowKeys.length === 0) {
                windowContainer.innerHTML = '<span style="color: #999;">Empty</span>';
            } else {
                windowKeys.forEach(char => {
                    const box = document.createElement('div');
                    box.className = 'variable-box';
                    const matches = s1Count[char] === windowCount[char];
                    if (matches) {
                        box.style.borderColor = '#4caf50';
                        box.style.background = '#e8f5e9';
                    } else {
                        box.style.borderColor = '#ff9800';
                        box.style.background = '#fff3e0';
                    }
                    box.innerHTML = `<div class="variable-name">'${char}'</div><div class="variable-value">${windowCount[char]}

        </div>`;
                    windowContainer.appendChild(box);
                });
            }
        }

        function step() {
            if (phase === 'init') {
                phase = 'firstWindow';
                windowCount = getCount(s2.substring(0, windowSize));
                renderS2();
                renderCounts();

                if (countsMatch(s1Count, windowCount)) {
                    phase = 'found';
                    document.getElementById('matchBox').style.display = 'block';
                    document.getElementById('matchBox').className = 'info-box secondary';
                    document.getElementById('matchBox').textContent = `✅ Found! "${s2.substring(0, windowSize)}" is a permutation of "${s1}"`;
                    document.getElementById('statusMessage').textContent = 'Permutation found in first window!';
                    document.getElementById('stepBtn').disabled = true;
                    stopAuto();
                } else {
                    document.getElementById('statusMessage').textContent =
                        `Initial window "${s2.substring(0, windowSize)}": Counts don't match s1. Sliding...`;
                }
                return;
            }

            if (phase === 'firstWindow') {
                phase = 'sliding';
            }

            if (phase === 'sliding') {
                if (windowStart >= s2.length - windowSize) {
                    phase = 'done';
                    document.getElementById('matchBox').style.display = 'block';
                    document.getElementById('matchBox').className = 'info-box highlight';
                    document.getElementById('matchBox').textContent = '❌ No permutation of s1 found in s2';
                    document.getElementById('statusMessage').textContent = 'Search complete. No match found.';
                    document.getElementById('stepBtn').disabled = true;
                    stopAuto();
                    return;
                }

                // Slide window
                const removeChar = s2[windowStart];
                windowCount[removeChar]--;
                if (windowCount[removeChar] === 0) delete windowCount[removeChar];

                windowStart++;
                const addChar = s2[windowStart + windowSize - 1];
                windowCount[addChar] = (windowCount[addChar] || 0) + 1;

                renderS2();
                renderCounts();

                const windowStr = s2.substring(windowStart, windowStart + windowSize);

                if (countsMatch(s1Count, windowCount)) {
                    phase = 'found';
                    document.getElementById('matchBox').style.display = 'block';
                    document.getElementById('matchBox').className = 'info-box secondary';
                    document.getElementById('matchBox').textContent = `✅ Found! "${windowStr}" is a permutation of "${s1}"`;
                    document.getElementById('statusMessage').textContent = `Permutation found at position ${windowStart}!`;
                    document.getElementById('stepBtn').disabled = true;
                    stopAuto();
                } else {
                    document.getElementById('statusMessage').textContent =
                        `Window "${windowStr}" at [${windowStart}]: Removed '${removeChar}', added '${addChar}'. Counts don't match.`;
                }
            }
        }

        function toggleAuto() {
            if (autoInterval) {
                stopAuto();
            } else {
                document.getElementById('autoBtn').textContent = 'Pause';
                autoInterval = setInterval(() => {
                    if (phase === 'done' || phase === 'found') {
                        stopAuto();
                    } else {
                        step();
                    }
                }, 1200);
            }
        }

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

        function reset() {
            stopAuto();
            phase = 'init';
            windowStart = 0;
            document.getElementById('stepBtn').disabled = false;
            document.getElementById('statusMessage').textContent =
                'Click "Step" or "Auto Run" to check if s2 contains a permutation of s1';
            init();
        }

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