Bernard Wong
  • Software Engineer
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    • Lowest Common Ancestor of a Binary Tree
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    • Longest Palindromic Substring
    • Longest Common Prefix
    • Isomorphic Strings
    • Integer to Roman
    • Frog Jump
    • Find the Difference
    • Find k closest elements to a given value
    • Longest Common Subsequence
    • Binary Search Tree from Sorted Array
    • Balanced Binary Tree
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    • O(1) Stack
    • k-th element to last of a LinkedList
    • Dedup LinkedList
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    • Escape HTML whitespace
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    • Container With Most Water
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    • Maximum Subarray
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    • Pow(x, n)
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    • Remove Nth Node From End of List
    • Reverse Integer
    • Roman to Integer
    • Rotate Array
    • Search a 2D Matrix
    • Shortest Word Distance
    • Two Sum III - Data structure design
    • Valid Parentheses
    • ZigZag Conversion
    • Quicksort
    • Add Two Numbers
    • Best Time to Buy and Sell Stock
    • Letter Combinations of a Phone Number
  • Data Structures
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  1. Problems

Isomorphic Strings

Given two strings s and t, determine if they are isomorphic.

Two strings are isomorphic if the characters in s can be replaced to get t.

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.

For example,

Given "egg", "add", return true.

Given "foo", "bar", return false.

Given "paper", "title", return true.

Note: You may assume both s and t have the same length.

def isIsomorphic(s: String, t: String): Boolean = {
  if (s.length != t.length) false
  else if (s.length == 0) true
  else {
    var mapping = Map[Char, Char]()
    for (i <- 0 until s.length) {
      mapping.get(s(i)) match {
        case Some(j) => {
          if (j != t(i)) return false
        }
        case None =>
          mapping += (s(i) -> t(i))
      }
    }
    true
  }
}

isIsomorphic("egg", "add")
isIsomorphic("foo", "bar")
isIsomorphic("paper", "title")

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Last updated 6 years ago