C#•7mo ago

How to fix a simple (hopefully) error?

I am doing a leetcode solution, and I have this so far:

public class Solution {
    public int HeightChecker(int[] heights) {
        int[] correctOrder = [];
        int amountWrong = 0;
        foreach(int i in heights) { 
            int iter = i;
            while (iter <= heights.Length){
                iter++;
                if (heights[i] < heights[iter]) {
                    int curr = heights[iter-1];
                   correctOrder[i] = correctOrder[heights[iter-1]];
                   heights[iter] = curr;
                }
            }
        }
        foreach(int i in heights) {
            if(heights[i] != correctOrder[i]){
                amountWrong++;
            }
        }
        return amountWrong;
    }
}

public class Solution {
    public int HeightChecker(int[] heights) {
        int[] correctOrder = [];
        int amountWrong = 0;
        foreach(int i in heights) { 
            int iter = i;
            while (iter <= heights.Length){
                iter++;
                if (heights[i] < heights[iter]) {
                    int curr = heights[iter-1];
                   correctOrder[i] = correctOrder[heights[iter-1]];
                   heights[iter] = curr;
                }
            }
        }
        foreach(int i in heights) {
            if(heights[i] != correctOrder[i]){
                amountWrong++;
            }
        }
        return amountWrong;
    }
}

I am getting this error

37 Replies

samisaskinnyqueenOP•7mo ago

I'm a beginner so if anything here is bad practice please let me know

Jimmacle•7mo ago

index out of range means you tried to access an array element that doesn't exist valid array indexes are from 0 to 1 less than the length of the array also, arrays are fixed size so if you're trying to put elements into an empty array it won't work

samisaskinnyqueenOP•7mo ago

so how should i do it instead

Jimmacle•7mo ago

make the array large enough to hold the data you want to put in it, or use a List which automatically expands to add items

samisaskinnyqueenOP•7mo ago

so would making correctOrder a list fix that error?

Jimmacle•7mo ago

if you change to a list and call Add, that would be one solution or just make the array big enough to hold all the heights like var correctOrder = new int[heights.Length];

samisaskinnyqueenOP•7mo ago

I switched it to a list looks like a similar if not the same error

samisaskinnyqueenOP•7mo ago

Jimmacle•7mo ago

and call Add you have to do that to put new items in a list

samisaskinnyqueenOP•7mo ago

can add put it in a specific spot

Jimmacle•7mo ago

you could use Insert for that

samisaskinnyqueenOP•7mo ago

Ill try that real quick' Still the same error

public class Solution {
    public int HeightChecker(int[] heights) {
        List<int> correctOrder = new List<int>();
        int amountWrong = 0;
        foreach(int i in heights) { 
            int iter = i;
            while (iter <= heights.Length){
                iter++;
                if (heights[i] < heights[iter]) {
                    int curr = heights[iter-1];
                   correctOrder.Insert(iter-1, correctOrder[heights[iter-1]]);
                   correctOrder.Insert(iter, curr);
                }
            }
        }
        foreach(int i in heights) {
            if(heights[i] != correctOrder[i]){
                amountWrong++;
            }
        }
        return amountWrong;
    }
}

public class Solution {
    public int HeightChecker(int[] heights) {
        List<int> correctOrder = new List<int>();
        int amountWrong = 0;
        foreach(int i in heights) { 
            int iter = i;
            while (iter <= heights.Length){
                iter++;
                if (heights[i] < heights[iter]) {
                    int curr = heights[iter-1];
                   correctOrder.Insert(iter-1, correctOrder[heights[iter-1]]);
                   correctOrder.Insert(iter, curr);
                }
            }
        }
        foreach(int i in heights) {
            if(heights[i] != correctOrder[i]){
                amountWrong++;
            }
        }
        return amountWrong;
    }
}

Jimmacle•7mo ago

correctOrder[heights[iter-1]] there will not be anything here, the list is empty

samisaskinnyqueenOP•7mo ago

should i just make correctOrder the same as heights but in list form in the beginning is that possible

Jimmacle•7mo ago

if your "correct order" is a known fixed size there's no reason to use the list

samisaskinnyqueenOP•7mo ago

then why'd you tell me to

Jimmacle•7mo ago

it sounds like what you want is https://discord.com/channels/143867839282020352/1249757566041325718/1249759651784822947

MODiX•7mo ago

Jimmacle

or just make the array big enough to hold all the heights like var correctOrder = new int[heights.Length];

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Jimmacle•7mo ago

i'm giving you multiple options, not the answer

samisaskinnyqueenOP•7mo ago

which option is the best then

Jimmacle•7mo ago

that's up to you, i have no idea what the actual problem being solved is i'm just going based off of a code snippet lists are generally for collections that change size, arrays can be used for collections that are always the same size

samisaskinnyqueenOP•7mo ago

so array would make more sense but i dont understand where i am getting a negative index

Jimmacle•7mo ago

foreach(int i in heights) seems off this will give you the values in heights, not the indexes are you sure you don't want a for loop?

samisaskinnyqueenOP•7mo ago

i need all the values, then i am sorting them smallest to biggest then comparing the new sorted array to the old one to see how many are wrong should i use a for loop?

samisaskinnyqueenOP•7mo ago

public class Solution {
    public int HeightChecker(int[] heights) {
        int[] correctOrder= new int[heights.Length];
        int amountWrong = 0;
        foreach(int i in heights) { 
            int iter = i;
            while (iter <= heights.Length){
                iter++;
                if (heights[i] < heights[iter]) {
                    int curr = heights[iter-1];
                   correctOrder[iter-1] = heights[iter-1];
                   correctOrder[iter] = curr;
                }
            }
        }
        foreach(int i in heights) {
            if(heights[i] != correctOrder[i]){
                amountWrong++;
            }
        }
        return amountWrong;
    }
}

public class Solution {
    public int HeightChecker(int[] heights) {
        int[] correctOrder= new int[heights.Length];
        int amountWrong = 0;
        foreach(int i in heights) { 
            int iter = i;
            while (iter <= heights.Length){
                iter++;
                if (heights[i] < heights[iter]) {
                    int curr = heights[iter-1];
                   correctOrder[iter-1] = heights[iter-1];
                   correctOrder[iter] = curr;
                }
            }
        }
        foreach(int i in heights) {
            if(heights[i] != correctOrder[i]){
                amountWrong++;
            }
        }
        return amountWrong;
    }
}

updated code, similar error

Jimmacle•7mo ago

if you need the index, use a for loop your code doesn't make sense because you're using the actual height value as an index into the array

samisaskinnyqueenOP•7mo ago

i need the values, no?

Jimmacle•7mo ago

i is not storing an index in your code, it's storing a height then you're trying to use it as an index into the arrays, which is probably where your bad index is coming from

samisaskinnyqueenOP•7mo ago

switched it and im still getting that same error ^

samisaskinnyqueenOP•7mo ago

Jimmacle•7mo ago

i <= heights.Length remember what i said about valid indexes heights.Length would be 1 past the end of the array

samisaskinnyqueenOP•7mo ago

okay that makes sense so heights.Length-1 then

Jimmacle•7mo ago

or just i < heights.Length

samisaskinnyqueenOP•7mo ago

same error still

Jimmacle•7mo ago

then you have more places where you're making mistakes can you run this code in an actual IDE with a debugger? it will tell you exactly which line is causing the exception

samisaskinnyqueenOP•7mo ago

yeah give me a second

blueberriesiftheywerecats•7mo ago

You have 2 of that checks, did you change both? And it reminds me of bubble sort, isnt it? Can you show full code?

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How to fix a simple (hopefully) error?