{"id":1051,"date":"2025-09-01T18:18:41","date_gmt":"2025-09-01T12:48:41","guid":{"rendered":"https:\/\/codeanddebug.in\/blog\/?p=1051"},"modified":"2025-09-01T18:18:42","modified_gmt":"2025-09-01T12:48:42","slug":"isomorphic-strings","status":"publish","type":"post","link":"https:\/\/codeanddebug.in\/blog\/isomorphic-strings\/","title":{"rendered":"Isomorphic Strings | Leetcode 205 | Optimal Hash Map Solution"},"content":{"rendered":"\n

The Isomorphic Strings<\/strong> problem asks us to determine if two strings s<\/code> and t<\/code> are isomorphic<\/strong>.<\/p>\n\n\n\n

Two strings are isomorphic<\/strong> if the characters in one string can be replaced to get the other string, while maintaining the following conditions:<\/p>\n\n\n\n

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  1. Each character in s<\/code> must map to exactly one character in t<\/code>.<\/li>\n\n\n\n
  2. No two characters in s<\/code> can map to the same character in t<\/code>.<\/li>\n\n\n\n
  3. The mapping must be consistent across the entire string.<\/li>\n<\/ol>\n\n\n\n

    Here’s the [Problem Link<\/span><\/mark><\/a><\/strong>] to begin with.<\/p>\n\n\n\n

    \n\n\n\n

    Examples<\/h3>\n\n\n\n

    Example 1<\/strong><\/p>\n\n\n\n

    <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
    Input<\/span>: <\/span>s = "egg", t = "add"<\/span><\/span>\nOutput<\/span>: <\/span>true<\/span><\/span>\nExplanation<\/span>: <\/span>'e'<\/span> <\/span>\u2192 'a', 'g' \u2192 'd'.<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
    Example 2<\/strong><\/p>\n\n\n\n
    <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
    Input<\/span>: <\/span>s = "foo", t = "bar"<\/span><\/span>\nOutput<\/span>: <\/span>false<\/span><\/span>\nExplanation<\/span>: <\/span>'o'<\/span> <\/span>would need to map to both 'o' and 'r', which is not possible.<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
    Example 3<\/strong><\/p>\n\n\n\n
    <\/circle><\/circle><\/circle><\/g><\/svg><\/span><\/path><\/path><\/svg><\/span>
    Input<\/span>: <\/span>s = "paper", t = "title"<\/span><\/span>\nOutput<\/span>: <\/span>true<\/span><\/span>\nExplanation<\/span>: <\/span>'p'<\/span> <\/span>\u2192 't', 'a' \u2192 'i', 'e' \u2192 'l', 'r' \u2192 'e'.<\/span><\/span><\/code><\/pre><\/div>\n\n\n\n
    \n\n\n\n
    Intuition and Approach<\/h2>\n\n\n\n
    The key to solving Isomorphic Strings<\/strong> is checking for consistent one-to-one mappings<\/strong> between the characters of s<\/code> and t<\/code>.<\/p>\n\n\n\n
      \n
    1. Use two dictionaries (hash maps):\n