String Transforms Into Another String
<p>Given two strings <code>str1</code> and <code>str2</code> of the same length, determine whether you can transform <code>str1</code> into <code>str2</code> by doing <strong>zero or more</strong> <em>conversions</em>.</p>

<p>In one conversion you can convert <strong>all</strong> occurrences of one character in <code>str1</code> to <strong>any</strong> other lowercase English character.</p>

<p>Return <code>true</code> if and only if you can transform <code>str1</code> into <code>str2</code>.</p>

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

<pre>
<strong>Input:</strong> str1 = &quot;aabcc&quot;, str2 = &quot;ccdee&quot;
<strong>Output:</strong> true
<strong>Explanation: </strong>Convert &#39;c&#39; to &#39;e&#39; then &#39;b&#39; to &#39;d&#39; then &#39;a&#39; to &#39;c&#39;. Note that the order of conversions matter.
</pre>

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

<pre>
<strong>Input:</strong> str1 = &quot;leetcode&quot;, str2 = &quot;codeleet&quot;
<strong>Output:</strong> false
<strong>Explanation: </strong>There is no way to transform str1 to str2.
</pre>

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

<ul>
	<li><code>1 &lt;= str1.length == str2.length &lt;= 10<sup>4</sup></code></li>
	<li><code>str1</code> and <code>str2</code> contain only lowercase English letters.</li>
</ul>
Graph; Hash Table; String
class Solution {
public:
    bool canConvert(string str1, string str2) {
        if (str1 == str2) {
            return true;
        }
        int cnt[26]{};
        int m = 0;
        for (char& c : str2) {
            if (++cnt[c - 'a'] == 1) {
                ++m;
            }
        }
        if (m == 26) {
            return false;
        }
        int d[26]{};
        for (int i = 0; i < str1.size(); ++i) {
            int a = str1[i] - 'a';
            int b = str2[i] - 'a';
            if (d[a] == 0) {
                d[a] = b + 1;
            } else if (d[a] != b + 1) {
                return false;
            }
        }
        return true;
    }
};