#1805: Number of Different Integers in a String; solution & tests.

Author: vetalapo

c-sharp/Problems/arrays-and-hashing/NumberOfDifferentIntegersInAString.cs

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+/**
+ * 1805
+ * Number of Different Integers in a String
+ **
+ * You are given a string word
+ * that consists of digits and lowercase English letters.
+ * You will replace every non-digit character with a space.
+ * For example, "a123bc34d8ef34" will become " 123  34 8  34".
+ * Notice that you are left with some integers
+ * that are separated by at least one space: "123", "34", "8", and "34".
+ *
+ * Return the number of different integers
+ * after performing the replacement operations on word.
+ * Two integers are considered different
+ * if their decimal representations without any leading zeros are different.
+ *
+ * Example 1:
+ *   Input: word = "a123bc34d8ef34"
+ *   Output: 3
+ *   Explanation:
+ *     The three different integers are "123", "34", and "8".
+ *     Notice that "34" is only counted once.
+ *
+ * Example 2:
+ *   Input: word = "leet1234code234"
+ *   Output: 2
+ *
+ * Example 3:
+ *   Input: word = "a1b01c001"
+ *   Output: 1
+ *   Explanation:
+ *     The three integers "1", "01", and "001" all represent the same integer because
+ *     the leading zeros are ignored when comparing their decimal values.
+ *
+ * Constraints:
+ *   • 1 <= word.length <= 1000
+ *   • word consists of digits and lowercase English letters.
+ *
+ * Hint 1:
+ *   Try to split the string so that each integer is in a different string.
+ *
+ * Hint 2:
+ *   Try to remove each integer's leading zeroes
+ *   and compare the strings to find how many of them are unique.
+ **
+ * https://leetcode.com/problems/number-of-different-integers-in-a-string/
+***/
+
+using System.Collections.Generic;
+
+namespace Problems;
+
+public class NumberOfDifferentIntegersInAString
+{
+    public int NumDifferentIntegers( string word )
+    {
+        HashSet<string> nums = [];
+
+        for ( int i = 0; i < word.Length; i++ )
+        {
+            if ( char.IsDigit( word[i] ) )
+            {
+                int j = i + 1;
+
+                while ( j < word.Length && char.IsDigit( word[j] ) )
+                {
+                    j++;
+                }
+
+                while ( i < j - 1 && word[i] == '0' )
+                {
+                    i++;
+                }
+
+                nums.Add( word[i..j] );
+
+                i = j;
+            }
+        }
+
+        return nums.Count;
+    }
+}

c-sharp/Tests/arrays-and-hashing/NumberOfDifferentIntegersInAStringTests.cs

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+using NUnit.Framework;
+
+using Problems;
+
+public class NumberOfDifferentIntegersInAStringTests
+{
+    [TestCase( "a123bc34d8ef34", ExpectedResult = 3 )]
+    [TestCase( "leet1234code234", ExpectedResult = 2 )]
+    [TestCase( "a1b01c001", ExpectedResult = 1 )]
+    public int NumDifferentIntegersTest( string word ) =>
+        new NumberOfDifferentIntegersInAString().NumDifferentIntegers( word );
+}