Udemy: Master Coding Interview - Coding Problems - #52
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using System;
using System.Collections.Generic;
// Given 2 arrays, create a function that lets a user know (true/false)
// whether these two arrays contain any common items
// For Example:
// const array1 = ['a', 'b', 'c', 'x'];
// const array1 = ['z', 'y', 'i'];
// should return false.
// ----------
// const array1 = ['a', 'b', 'c', 'x'];
// const array1 = ['z', 'y', 'x'];
// should return true.
// Naive approach: Loop through first list, then another inner loop through
// second list, comparing values. This is slow, O(n^2) due to nested loops.
// Next approach: Add elements to hash set? Sort lists?
class MainClass {
static char[] array1 = {'a', 'b', 'c', 'x'};
static char[] array2 = {'z', 'y', 'x'};
static char[] array3 = {'z', 'y', 'i'};
static void Main() {
Console.WriteLine("Result = " + containsCommonItems2(array1, array2));
}
// O(a*b)
static bool containsCommonItems(char[] array1, char[] array2) {
for (int i = 0; i < array1.Length; i++) {
for (int j = 0; j < array2.Length; j++) {
if (array1[i] == array2[j]) {
return true;
}
}
}
return false;
}
// O(a+b)
static bool containsCommonItems2(char[] array1, char[] array2) {
// Loop through first array and create object where
// properties = items in array.
HashSet<char> set = new HashSet<char>();
for (int i = 0; i < array1.Length; i++) {
set.Add(array1[i]);
}
// Loop through second array and check if item in second array
// exists on created object.
for (int j = 0; j < array2.Length; j++) {
if (set.Contains(array2[j])) {
return true;
}
}
return false;
}
}
Csharp
INFO