C#•3mo ago

changing a boolean value outside a loop from inside a loop

so im doing a leetcode challenge to detect duplicate numbers in an array, im trying to use the duplicate bool value so when a duplicate is detected, it edits the duplicate value to true and exits the loop, no matter what i try the output is always false however

public class Solution 
{

    int[] nums ={1, 2, 3, 1};

    public bool ContainsDuplicate(int[] nums)
    {
        bool running = true;
        bool duplicate = false;
        int count = 0;
        int count2 = 0;

        while (running == true)
        {
            foreach (int x in nums)
            {
                foreach (int z in nums)
                {
                    
                    if (z == nums[count])
                    {
                        count2++;
                        break;
                    }
                    
                    count++;
                }
                if (count2 > 1)
                    {
                        running = false;
                        duplicate = true;
                    }
                count2 = 0;
                
            }
            running = false;            
        }
        return duplicate;
    }
}

public class Solution 
{

    int[] nums ={1, 2, 3, 1};

    public bool ContainsDuplicate(int[] nums)
    {
        bool running = true;
        bool duplicate = false;
        int count = 0;
        int count2 = 0;

        while (running == true)
        {
            foreach (int x in nums)
            {
                foreach (int z in nums)
                {
                    
                    if (z == nums[count])
                    {
                        count2++;
                        break;
                    }
                    
                    count++;
                }
                if (count2 > 1)
                    {
                        running = false;
                        duplicate = true;
                    }
                count2 = 0;
                
            }
            running = false;            
        }
        return duplicate;
    }
}

11 Replies

zzzOP•3mo ago

from what i can see when i try and set duplicate to true it is not accessing the variable outside the loop any help appreciated im still new

Angius•3mo ago

Or, what is much more likely than the language completely breaking, count2 is never more than 1

zzzOP•3mo ago

its probably not the most efficient way of solving the problem how? it loops through whole array and increases count everytime there is a same number

Angius•3mo ago

Well, the easiest way to figure it out is to place some breakpoints and debug it

zzzOP•3mo ago

leetcode isnt good for that is it i dont have vs on this pc it only shows me my outputs for each test case when i run it ill try it on studio tomorrow

Angius•3mo ago

Then trying to figure it out really won't be easy

zzzOP•3mo ago

Angius•3mo ago

You can run this code on Sharplab and do some good ol' Console.WriteLine() debugging

zzzOP•3mo ago

ill just watch a tutorial ig p[robably a more efficient way anyway thx tho

Dinosaure•3mo ago

As stated, when a duplicate is found, count2 is incremented once; then, the condition for the bool change is count2 > 1, which won’t happen ever. Maybe the condition could be count2 >= 1? Or maybe you can use LINQ, with bool duplicate = nums.ToLookup(n => n).Any(g => g.Count() > 1); (requires using System.Linq as a header), instead of the entire while block?

Dinosaure•3mo ago

@zzz if you want to briefly test some C# code, you can use sharplab.io, it’s an online dev pad, where you'll find nearly everything you need for proof of concepts.

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changing a boolean value outside a loop from inside a loop