algorithm-neet-code-top-150-python-visual/visual/0013_roman_to_integer.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>Roman to Integer - LeetCode 13</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">#13</span> Roman to Integer</h1>
            <p>Convert a Roman numeral to an integer.</p>
            <div class="problem-meta">
                <span class="meta-tag">Math</span>
                <span class="meta-tag">String</span>
                <span class="meta-tag">Easy</span>
            </div>
            <div class="file-ref">
                📄 Python: <code>python/0013_roman_to_integer/0013_roman_to_integer.py</code>
            </div>

        </div>

        <div class="explanation-panel">
            <h4>🧠 How It Works (Layman's Terms)</h4>
            <p>This algorithm solves the problem <strong>step by step</strong>:</p>
            <ul>
                <li><strong>Understand:</strong> Parse the input data</li>
                <li><strong>Process:</strong> Apply the core logic</li>
                <li><strong>Optimize:</strong> Use efficient data structures</li>
                <li><strong>Return:</strong> Output the computed result</li>
            </ul>
        </div>


        <div class="visualization-section">
            <h3>🎬 Step-by-Step Visualization</h3>
            <div class="controls">
                <button id="stepBtn">Step</button>
                <button id="autoBtn">Auto Run</button>
                <button id="resetBtn">Reset</button>
            </div>
            <svg id="mainSvg" width="800" height="380"></svg>
            <div class="status-message" id="status">Click "Step" to convert Roman to integer</div>
        </div>

        <div class="code-section">
            <h3>💻 Python Solution</h3>
            <div class="code-block">
                <pre><span class="keyword">def</span> <span class="function">romanToInt</span>(s: <span class="class-name">str</span>) -> int:
    values = {<span class="string">'I'</span>: <span class="number">1</span>, <span class="string">'V'</span>: <span class="number">5</span>, <span class="string">'X'</span>: <span class="number">10</span>, <span class="string">'L'</span>: <span class="number">50</span>,
              <span class="string">'C'</span>: <span class="number">100</span>, <span class="string">'D'</span>: <span class="number">500</span>, <span class="string">'M'</span>: <span class="number">1000</span>}

    total = <span class="number">0</span>
    prev_value = <span class="number">0</span>

    <span class="comment"># Process right to left</span>
    <span class="keyword">for</span> char <span class="keyword">in</span> <span class="function">reversed</span>(s):
        curr = values[char]
        <span class="keyword">if</span> curr >= prev_value:
            total += curr
        <span class="keyword">else</span>:
            total -= curr  <span class="comment"># Subtraction case</span>
        prev_value = curr

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

    <script>
        const romanValues = {'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000};
        const testCases = ["MCMXCIV", "III", "LVIII", "IX"];

        let s = "MCMXCIV";
        let i;
        let total = 0;
        let prevValue = 0;
        let phase = 'processing';

        const width = 800, height = 380;
        const svg = d3.select("#mainSvg");
        let autoTimer = null;
        let autoRunning = false;

        function draw() {
            svg.selectAll("*").remove();

            const cellWidth = 60, startX = 100, startY = 80;

            // Title
            svg.append("text")
                .attr("x", width / 2).attr("y", 30)
                .attr("text-anchor", "middle")
                .attr("font-weight", "bold")
                .text(`Converting "${s}" to Integer (Right to Left)`);

            // Draw Roman characters
            for (let idx = 0; idx < s.length; idx++) {
                const x = startX + idx * cellWidth;
                const isProcessed = idx > i;
                const isCurrent = idx === i;

                svg.append("rect")
                    .attr("x", x).attr("y", startY)
                    .attr("width", cellWidth - 5).attr("height", 55)
                    .attr("rx", 8)
                    .attr("fill", isCurrent ? "#fef3c7" : (isProcessed ? "#d1fae5" : "#e3f2fd"))
                    .attr("stroke", isCurrent ? "#f59e0b" : (isProcessed ? "#10b981" : "#1976d2"))
                    .attr("stroke-width", isCurrent ? 3 : 2);

                svg.append("text")
                    .attr("x", x + (cellWidth - 5) / 2)
                    .attr("y", startY + 30)
                    .attr("text-anchor", "middle")
                    .attr("font-size", "26px")
                    .attr("font-weight", "bold")
                    .text(s[idx]);

                svg.append("text")
                    .attr("x", x + (cellWidth - 5) / 2)
                    .attr("y", startY + 48)
                    .attr("text-anchor", "middle")
                    .attr("font-size", "12px")
                    .attr("fill", "#666")
                    .text(romanValues[s[idx]]);
            }

            // Direction arrow
            svg.append("text")
                .attr("x", startX + s.length * cellWidth + 20)
                .attr("y", startY + 30)
                .attr("font-size", "24px")
                .text("←");

            svg.append("text")
                .attr("x", startX + s.length * cellWidth + 50)
                .attr("y", startY + 35)
                .attr("font-size", "12px")
                .attr("fill", "#666")
                .text("Direction");

            // Variables display
            const varsY = 180;
            const vars = [
                { name: "Current Value", value: i >= 0 ? romanValues[s[i]] : "-" },
                { name: "Previous Value", value: prevValue },
                { name: "Total", value: total }
            ];

            vars.forEach((v, idx) => {
                const x = 100 + idx * 200;

                svg.append("rect")
                    .attr("x", x).attr("y", varsY)
                    .attr("width", 160).attr("height", 60)
                    .attr("rx", 10)
                    .attr("fill", idx === 2 ? "#e8f5e9" : "#f5f5f5")
                    .attr("stroke", idx === 2 ? "#4caf50" : "#ddd");

                svg.append("text")
                    .attr("x", x + 80).attr("y", varsY + 22)
                    .attr("text-anchor", "middle")
                    .attr("font-size", "12px")
                    .attr("fill", "#666")
                    .text(v.name);

                svg.append("text")
                    .attr("x", x + 80).attr("y", varsY + 48)
                    .attr("text-anchor", "middle")
                    .attr("font-size", "22px")
                    .attr("font-weight", "bold")
                    .text(v.value);
            });

            // Logic explanation
            if (i >= 0 && phase === 'processing') {
                const curr = romanValues[s[i]];
                const logicY = 280;
                const isSubtraction = curr < prevValue;

                svg.append("rect")
                    .attr("x", 150).attr("y", logicY)
                    .attr("width", 500).attr("height", 45)
                    .attr("rx", 8)
                    .attr("fill", isSubtraction ? "#fee2e2" : "#d1fae5")
                    .attr("stroke", isSubtraction ? "#ef4444" : "#10b981");

                svg.append("text")
                    .attr("x", 400).attr("y", logicY + 28)
                    .attr("text-anchor", "middle")
                    .attr("font-size", "14px")
                    .text(isSubtraction
                        ? `${curr} < ${prevValue}: SUBTRACT → total = ${total} - ${curr}`
                        : `${curr} ≥ ${prevValue}: ADD → total = ${total} + ${curr}`);
            }

            // Final result
            if (phase === 'done') {
                svg.append("rect")
                    .attr("x", width / 2 - 120).attr("y", 310)
                    .attr("width", 240).attr("height", 55)
                    .attr("rx", 12)
                    .attr("fill", "#d1fae5").attr("stroke", "#10b981")
                    .attr("stroke-width", 2);

                svg.append("text")
                    .attr("x", width / 2).attr("y", 345)
                    .attr("text-anchor", "middle")
                    .attr("font-size", "24px")
                    .attr("font-weight", "bold")
                    .attr("fill", "#10b981")
                    .text(`${s} = ${total}`);
            }
        }

        function step() {
            if (phase === 'done') return false;

            if (i < 0) {
                phase = 'done';
                document.getElementById("status").textContent = `Done! ${s} = ${total}`;
                draw();
                return false;
            }

            const curr = romanValues[s[i]];

            if (curr >= prevValue) {
                total += curr;
                document.getElementById("status").textContent =
                    `'${s[i]}' (${curr}) ≥ prev (${prevValue}): Add ${curr}. Total = ${total}`;
            } else {
                total -= curr;
                document.getElementById("status").textContent =
                    `'${s[i]}' (${curr}) < prev (${prevValue}): Subtract ${curr}. Total = ${total}`;
            }

            prevValue = curr;
            i--;

            draw();
            return i >= 0;
        }

        function reset() {
            i = s.length - 1;
            total = 0;
            prevValue = 0;
            phase = 'processing';
            if (autoTimer) clearInterval(autoTimer);
            autoRunning = false;
            document.getElementById("autoBtn").textContent = "Auto Run";
            document.getElementById("status").textContent = 'Click "Step" to convert Roman to integer';
            draw();
        }

        function autoRun() {
            if (autoRunning) {
                clearInterval(autoTimer);
                autoRunning = false;
                document.getElementById("autoBtn").textContent = "Auto Run";
            } else {
                autoRunning = true;
                document.getElementById("autoBtn").textContent = "Pause";
                autoTimer = setInterval(() => {
                    if (!step()) {
                        clearInterval(autoTimer);
                        autoRunning = false;
                        document.getElementById("autoBtn").textContent = "Auto Run";
                    }
                }, 800);
            }
        }

        document.getElementById("stepBtn").addEventListener("click", step);
        document.getElementById("autoBtn").addEventListener("click", autoRun);
        document.getElementById("resetBtn").addEventListener("click", reset);

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