C#•17mo ago

❔ C# Recursion Output problem

Here's a piece of code (formatted by benqbenq) in C# for finding the sum of triplets that are closest to 1. The code outputs the sum, but I want it to output the triplets that produced the sum. I'm a noob at C# and recursion is difficult, can anyone help?

int[] arr = new int[] { -1, 2, 1, -4 };
int target = 1;
int arrSize = arr.Length;
int minDiff = int.MaxValue;
int answer = 0;

FindClosestTriplet(
    arr,
    size: arrSize,
    targetSum: target,
    currentCount: 0, 
    currentSum: 0, 
    currentIndex: 0, 
    closestSum: ref answer,
    minDifference: ref minDiff);

Console.WriteLine(answer);

static void FindClosestTriplet(int[] array, int size, int targetSum, int currentCount, int currentSum, int currentIndex, ref int closestSum, ref int minDifference)
{
    // Return when reaching the end of the array
    // If we have picked three elements so far, check if the sum is closest to our "targetSum"
    if (currentIndex == size)
    {
        if (currentCount == 3)
        {
            int currentDifference = Math.Abs(targetSum - currentSum);
            if (currentDifference < minDifference)
            {
                minDifference = currentDifference;
                closestSum = currentSum;
            }
        }
        return;
    }

    // Pick this number
    FindClosestTriplet(array, size, targetSum, currentCount + 1, currentSum + array[currentIndex], currentIndex + 1, ref closestSum, ref minDifference);

    // Don't pick this number
    FindClosestTriplet(array, size, targetSum, currentCount, currentSum, currentIndex + 1, ref closestSum, ref minDifference);
}

int[] arr = new int[] { -1, 2, 1, -4 };
int target = 1;
int arrSize = arr.Length;
int minDiff = int.MaxValue;
int answer = 0;

FindClosestTriplet(
    arr,
    size: arrSize,
    targetSum: target,
    currentCount: 0, 
    currentSum: 0, 
    currentIndex: 0, 
    closestSum: ref answer,
    minDifference: ref minDiff);

Console.WriteLine(answer);

static void FindClosestTriplet(int[] array, int size, int targetSum, int currentCount, int currentSum, int currentIndex, ref int closestSum, ref int minDifference)
{
    // Return when reaching the end of the array
    // If we have picked three elements so far, check if the sum is closest to our "targetSum"
    if (currentIndex == size)
    {
        if (currentCount == 3)
        {
            int currentDifference = Math.Abs(targetSum - currentSum);
            if (currentDifference < minDifference)
            {
                minDifference = currentDifference;
                closestSum = currentSum;
            }
        }
        return;
    }

    // Pick this number
    FindClosestTriplet(array, size, targetSum, currentCount + 1, currentSum + array[currentIndex], currentIndex + 1, ref closestSum, ref minDifference);

    // Don't pick this number
    FindClosestTriplet(array, size, targetSum, currentCount, currentSum, currentIndex + 1, ref closestSum, ref minDifference);
}

3 Replies

HimmDawg•17mo ago

You gotta drag either the 3 indices or the three numbers itself through your recursive calls So add either of those to the parameter list of your recursive function. Then you gotta figure out, how to populate them

EmperMinerOP•17mo ago

thank you

Accord•17mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ C# Recursion Output problem