algorithm-neet-code-top-150-python-visual/visual/0139_word_break.html at main · kimtth/algorithm-neet-code-top-150-python-visual · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>LC 139: Word Break - 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">#139</span> Word Break</h1>
            <p>Given a string s and a dictionary of words, determine if s can be segmented into a space-separated sequence of one or more dictionary words.</p>
            <div class="problem-meta">
                <span class="meta-tag">📊 Dynamic Programming</span>
                <span class="meta-tag">🔤 String</span>
                <span class="meta-tag">⏱️ O(n²)</span>
                <span class="meta-tag">💾 O(n)</span>
            </div>
            <div class="file-ref">
                📄 Python: <code>python/0139_word_break/0139_word_break.py</code>
            </div>
            </div>

        <div class="explanation-panel">
            <h4>🧠 How It Works (Layman's Terms)</h4>
            <p>We ask: <strong>"Can I break this string into dictionary words?"</strong></p>
            <ul>
                <li><strong>dp[i]:</strong> "Can s[0:i] be broken into valid words?"</li>
                <li><strong>Base case:</strong> dp[0] = True (empty string is valid)</li>
                <li><strong>For each position i:</strong> Check all possible splits. If dp[j] is true AND s[j:i] is a word, then dp[i] = True!</li>
                <li><strong>Answer:</strong> dp[len(s)] tells us if the whole string can be broken</li>
            </ul>
        </div>


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

            <div class="controls">
                <select id="exampleSelect" style="padding: 8px; border-radius: 5px; border: 2px solid #ddd;">
                    <option value="0">"leetcode" → ["leet", "code"]</option>
                    <option value="1">"applepenapple" → ["apple", "pen"]</option>
                    <option value="2">"catsandog" → ["cats", "dog", "sand", "and", "cat"]</option>
                </select>
                <button class="btn btn-primary" onclick="loadExample()">Load</button>
                <button class="btn btn-primary" onclick="step()">Step</button>
                <button class="btn btn-success" onclick="autoRun()">Auto Run</button>
                <button class="btn" style="background: #607d8b; color: white;" onclick="reset()">Reset</button>
            </div>

            <div class="status-message" id="statusMessage">
                Click Step to check if the string can be broken into words
            </div>

            <div style="margin-top: 20px;">
                <h4 style="margin-bottom: 10px;">🔤 String</h4>
                <div id="stringContainer" style="display: flex; gap: 3px; flex-wrap: wrap; padding: 15px; background: #f5f5f5; border-radius: 12px; justify-content: center;">
                </div>
            </div>

            <div style="margin-top: 20px;">
                <h4 style="margin-bottom: 10px;">📊 DP Array: dp[i] = "Can s[0:i] be broken?"</h4>
                <div id="dpContainer" style="display: flex; gap: 5px; flex-wrap: wrap; padding: 15px; background: #e3f2fd; border-radius: 12px; justify-content: center;">
                </div>
            </div>

            <div style="display: flex; gap: 30px; flex-wrap: wrap; margin-top: 20px;">
                <div style="flex: 1; min-width: 200px;">
                    <h4 style="margin-bottom: 10px;">📚 Dictionary</h4>
                    <div id="dictContainer" style="display: flex; flex-wrap: wrap; gap: 8px; padding: 15px; background: #f5f5f5; border-radius: 12px;">
                    </div>
                </div>
                <div style="flex: 1; min-width: 200px;">
                    <h4 style="margin-bottom: 10px;">🔍 Current Check</h4>
                    <div id="checkContainer" style="padding: 15px; background: #fff3e0; border-radius: 12px; min-height: 80px;">
                        <span style="color: #999;">-</span>
                    </div>

                    <h4 style="margin-top: 20px; margin-bottom: 10px;">✅ Result</h4>
                    <div id="resultContainer" style="padding: 20px; background: #e8f5e9; border-radius: 12px; text-align: center; font-size: 1.3em; font-weight: bold;">
                        -
                    </div>
                </div>
            </div>
        </div>
        <div class="code-section">
            <h3>💻 Python Solution</h3>
            <div class="code-block">
                <pre><span class="keyword">def</span> <span class="function">word_break</span>(s, wordDict):
    dp = [<span class="keyword">False</span>] * (<span class="function">len</span>(s) + <span class="number">1</span>)
    dp[<span class="number">0</span>] = <span class="keyword">True</span>  <span class="comment"># Empty string is valid</span>
    word_set = <span class="function">set</span>(wordDict)

    <span class="keyword">for</span> i <span class="keyword">in</span> <span class="function">range</span>(<span class="number">1</span>, <span class="function">len</span>(s) + <span class="number">1</span>):
        <span class="keyword">for</span> j <span class="keyword">in</span> <span class="function">range</span>(i - <span class="number">1</span>, <span class="number">-1</span>, <span class="number">-1</span>):
            <span class="comment"># If s[0:j] is valid AND s[j:i] is a word</span>
            <span class="keyword">if</span> dp[j] <span class="keyword">and</span> s[j:<span class="class-name">i</span>] <span class="keyword">in</span> word_set:
                dp[i] = <span class="keyword">True</span>
                <span class="keyword">break</span>

    <span class="keyword">return</span> dp[<span class="function">len</span>(s)]</pre>
            </div>
        </div>
    </div>

    <script>
        const examples = [
            { s: "leetcode", dict: ["leet", "code"], result: true },
            { s: "applepenapple", dict: ["apple", "pen"], result: true },
            { s: "catsandog", dict: ["cats", "dog", "sand", "and", "cat"], result: false }
        ];

        let currentExample = examples[0];
        let s = currentExample.s;
        let wordDict = new Set(currentExample.dict);
        let dp = [];
        let i = 1;
        let j = 0;
        let done = false;
        let isRunning = false;
        let foundMatch = false;
        let currentSubstr = '';
        let highlightStart = -1;
        let highlightEnd = -1;

        function loadExample() {
            const idx = parseInt(document.getElementById('exampleSelect').value);
            currentExample = examples[idx];
            s = currentExample.s;
            wordDict = new Set(currentExample.dict);
            reset();
        }

        function renderString() {
            const container = document.getElementById('stringContainer');
            container.innerHTML = s.split('').map((char, idx) => {
                let bgColor = '#fff';
                let borderColor = '#ddd';

                if (idx >= highlightStart && idx < highlightEnd) {
                    bgColor = '#ff9800';
                    borderColor = '#f57c00';
                } else if (idx < i) {
                    bgColor = dp[idx + 1] ? '#c8e6c9' : '#ffcdd2';
                    borderColor = dp[idx + 1] ? '#a5d6a7' : '#ef9a9a';
                }

                return `
                    <div style="width: 35px; height: 40px; display: flex; flex-direction: column;
                                align-items: center; justify-content: center; background: ${bgColor};
                                border: 2px solid ${borderColor}; border-radius: 6px; font-weight: bold;">
                        <span>${char}</span>
                        <span style="font-size: 0.6em; color: #999;">${idx}</span>
                    </div>
                `;
            }).join('');
        }

        function renderDP() {
            const container = document.getElementById('dpContainer');
            container.innerHTML = dp.map((val, idx) => `
                <div style="display: flex; flex-direction: column; align-items: center; padding: 8px 12px;
                            background: ${val ? '#4caf50' : '#e0e0e0'};
                            border: 2px solid ${idx === i ? '#ff9800' : (val ? '#388e3c' : '#bdbdbd')};
                            border-radius: 6px; min-width: 45px;
                            ${idx === i ? 'box-shadow: 0 0 10px rgba(255,152,0,0.5);' : ''}">
                    <span style="font-size: 0.7em; color: ${val ? 'white' : '#666'};">dp[${idx}]</span>
                    <span style="font-weight: bold; color: ${val ? 'white' : '#333'};">${val ? 'T' : 'F'}</span>
                </div>
            `).join('');
        }

        function renderDict() {
            const container = document.getElementById('dictContainer');
            container.innerHTML = Array.from(wordDict).map(word => `
                <div style="padding: 8px 15px; background: ${word === currentSubstr ? '#4caf50' : '#667eea'};
                            color: white; border-radius: 6px; font-weight: bold;">
                    ${word}
                </div>
            `).join('');
        }

        function renderCheck() {
            const container = document.getElementById('checkContainer');
            if (i > s.length) {
                container.innerHTML = '<span style="color: #999;">Done</span>';
                return;
            }

            const substr = s.substring(j, i);
            const isWord = wordDict.has(substr);
            const dpValid = dp[j];

            container.innerHTML = `
                <div style="margin-bottom: 10px;">
                    <strong>Checking position i=${i}:</strong>
                </div>
                <div style="margin-bottom: 5px;">
                    s[${j}:${i}] = "<span style="color: ${isWord ? '#4caf50' : '#f44336'}; font-weight: bold;">${substr}</span>"
                </div>
                <div style="margin-bottom: 5px;">
                    In dictionary? <span style="color: ${isWord ? '#4caf50' : '#f44336'}; font-weight: bold;">${isWord ? 'YES' : 'NO'}</span>
                </div>
                <div>
                    dp[${j}] = ${dpValid} → ${dpValid && isWord ? '✅ dp[' + i + '] = True!' : '❌ Try next j'}

        </div>
            `;
        }

        function step() {
            if (done) {
                return;
            }

            if (i > s.length) {
                done = true;
                const result = dp[s.length];
                document.getElementById('resultContainer').innerHTML =
                    result ? '<span style="color: #4caf50;">✅ Can be broken!</span>' :
                             '<span style="color: #f44336;">❌ Cannot be broken</span>';
                document.getElementById('statusMessage').textContent =
                    result ? `Success! "${s}" can be segmented into dictionary words.` :
                             `Failed! "${s}" cannot be segmented into dictionary words.`;
                highlightStart = highlightEnd = -1;
                renderString();
                return;
            }

            const substr = s.substring(j, i);
            currentSubstr = wordDict.has(substr) ? substr : '';
            highlightStart = j;
            highlightEnd = i;

            if (dp[j] && wordDict.has(substr)) {
                dp[i] = true;
                document.getElementById('statusMessage').textContent =
                    `Found! dp[${j}]=True AND "${substr}" is a word → dp[${i}]=True`;

                // Move to next i
                i++;
                j = i - 1;
                foundMatch = false;
            } else {
                if (j > 0) {
                    j--;
                    document.getElementById('statusMessage').textContent =
                        `s[${j+1}:${i}]="${s.substring(j+1, i)}" not valid, trying j=${j}...`;
                } else {
                    document.getElementById('statusMessage').textContent =
                        `No valid split for position ${i}, dp[${i}] stays False`;
                    i++;
                    j = i - 1;
                }
            }

            renderString();
            renderDP();
            renderDict();
            renderCheck();
        }

        function autoRun() {
            if (isRunning) return;
            isRunning = true;

            const interval = setInterval(() => {
                if (done) {
                    clearInterval(interval);
                    isRunning = false;
                    return;
                }
                step();
            }, 600);
        }

        function reset() {
            dp = new Array(s.length + 1).fill(false);
            dp[0] = true;
            i = 1;
            j = 0;
            done = false;
            isRunning = false;
            foundMatch = false;
            currentSubstr = '';
            highlightStart = highlightEnd = -1;

            document.getElementById('statusMessage').textContent =
                `Check if "${s}" can be broken into words: [${Array.from(wordDict).join(', ')}]`;
            document.getElementById('resultContainer').textContent = '-';

            renderString();
            renderDP();
            renderDict();
            renderCheck();
        }

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