#2956: Find Common Elements between Two Arrays; solution & tests

Author: vetalapo

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

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+/**
+ * 2956
+ * Find Common Elements Between Two Arrays
+ **
+ * You are given two integer arrays nums1 and nums2 of sizes n and m, respectively.
+ * Calculate the following values:
+ *   • answer1 : the number of indices i such that nums1[i] exists in nums2.
+ *   • answer2 : the number of indices i such that nums2[i] exists in nums1.
+ *
+ * Return [answer1,answer2].
+ *
+ * Example 1:
+ *   Input: nums1 = [2,3,2], nums2 = [1,2]
+ *   Output: [2,1]
+ *
+ * Example 2:
+ *   Input: nums1 = [4,3,2,3,1], nums2 = [2,2,5,2,3,6]
+ *   Output: [3,4]
+ *   Explanation:
+ *     The elements at indices 1, 2, and 3 in nums1 exist in nums2 as well. So answer1 is 3.
+ *     The elements at indices 0, 1, 3, and 4 in nums2 exist in nums1. So answer2 is 4.
+ *
+ * Example 3:
+ *   Input: nums1 = [3,4,2,3], nums2 = [1,5]
+ *   Output: [0,0]
+ *   Explanation:
+ *     No numbers are common between nums1 and nums2, so answer is [0,0].
+ *
+ * Constraints:
+ *   • n == nums1.length
+ *   • m == nums2.length
+ *   • 1 <= n, m <= 100
+ *   • 1 <= nums1[i], nums2[i] <= 100
+ *
+ * Hint 1:
+ *   Since the constraints are small,
+ *   you can use brute force to solve the problem.
+ *
+ * Hint 2:
+ *   For each element i in nums1,
+ *   iterate over all elements of nums2 to find if it occurs.
+ **
+ * https://leetcode.com/problems/find-common-elements-between-two-arrays/
+***/
+
+namespace Problems;
+
+public class FindCommonElementsBetweenTwoArrays
+{
+    public int[] FindIntersectionValues( int[] nums1, int[] nums2 )
+    {
+        bool[] freq1 = new bool[101];
+        bool[] freq2 = new bool[101];
+
+        foreach ( int num in nums1 )
+        {
+            freq1[num] = true;
+        }
+
+        int numsCount2 = 0;
+
+        foreach ( int num in nums2 )
+        {
+            freq2[num] = true;
+
+            if ( freq1[num] )
+            {
+                numsCount2++;
+            }
+        }
+
+        int numsCount1 = 0;
+
+        foreach ( int num in nums1 )
+        {
+            if ( freq2[num] )
+            {
+                numsCount1++;
+            }
+        }
+
+        return [numsCount1, numsCount2];
+    }
+}

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

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+using NUnit.Framework;
+
+using Problems;
+
+public class FindCommonElementsBetweenTwoArraysTests
+{
+    [TestCase( new int[] { 2, 3, 2 }, new int[] { 1, 2 }, ExpectedResult = new int[] { 2, 1 } )]
+    [TestCase( new int[] { 4, 3, 2, 3, 1 }, new int[] { 2, 2, 5, 2, 3, 6 }, ExpectedResult = new int[] { 3, 4 } )]
+    [TestCase( new int[] { 3, 4, 2, 3 }, new int[] { 1, 5 }, ExpectedResult = new int[] { 0, 0 } )]
+    public int[] FindIntersectionValuesTest( int[] nums1, int[] nums2 ) =>
+        new FindCommonElementsBetweenTwoArrays().FindIntersectionValues( nums1, nums2 );
+}