<p>Given two strings <code>s</code> and <code>t</code>, <em>determine if they are isomorphic</em>.</p>
<p>Two strings <code>s</code> and <code>t</code> are isomorphic if the characters in <code>s</code> can be replaced to get <code>t</code>.</p>
<p>All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character, but a character may map to itself.</p>
<p>The strings <code>s</code> and <code>t</code> can not be made identical as <code>'o'</code> needs to be mapped to both <code>'a'</code> and <code>'r'</code>.</p>
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<p><strongclass="example">Example 3:</strong></p>
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<p><strong>Input:</strong><spanclass="example-io">s = "paper", t = "title"</span></p>