<p>Given two strings <code>word1</code> and <code>word2</code>, return <em>the minimum number of operations required to convert <code>word1</code> to <code>word2</code></em>.</p>

<p>You have the following three operations permitted on a word:</p>

<ul>
	<li>Insert a character</li>
	<li>Delete a character</li>
	<li>Replace a character</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> word1 = &quot;horse&quot;, word2 = &quot;ros&quot;
<strong>Output:</strong> 3
<strong>Explanation:</strong> 
horse -&gt; rorse (replace &#39;h&#39; with &#39;r&#39;)
rorse -&gt; rose (remove &#39;r&#39;)
rose -&gt; ros (remove &#39;e&#39;)
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> word1 = &quot;intention&quot;, word2 = &quot;execution&quot;
<strong>Output:</strong> 5
<strong>Explanation:</strong> 
intention -&gt; inention (remove &#39;t&#39;)
inention -&gt; enention (replace &#39;i&#39; with &#39;e&#39;)
enention -&gt; exention (replace &#39;n&#39; with &#39;x&#39;)
exention -&gt; exection (replace &#39;n&#39; with &#39;c&#39;)
exection -&gt; execution (insert &#39;u&#39;)
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>0 &lt;= word1.length, word2.length &lt;= 500</code></li>
	<li><code>word1</code> and <code>word2</code> consist of lowercase English letters.</li>
</ul>

constexpr int MAX_N = 5e2 + 5;
constinit int dp_i1[MAX_N]{};
class Solution {
public:
    int minDistance(string &word1, string &word2) {
        if (word1.size() < word2.size()) {
            std::swap(word1, word2);
        }
        int n = word1.size(), m = word2.size(), inf = 1e9;
        for (int j = 0; j <= m; ++j) {
            dp_i1[j] = m - j;
        }
        for (int i = n - 1; i >= 0; --i) {
            int dp_i1_j1 = dp_i1[m];
            dp_i1[m] = n - i;
            for (int j = m - 1; j >= 0; --j) {
                int dp_i1_j = dp_i1[j];
                dp_i1[j] = word1[i] == word2[j]
                    ? dp_i1_j1
                    : 1 + min(min(dp_i1[j + 1], dp_i1_j), dp_i1_j1);
                dp_i1_j1 = dp_i1_j;
            }
        }
        return dp_i1[0];
    }
};
9463