Index of the items that have the most addition and subtraction-CodePudding

I have two arrays and I want to find the index of the items that have the most addition and subtraction. for example:

var arrayA = new int[] { 1, -2, 3, 4, 15, 7, 9, 2 };
var arrayB = new int[] { 6, 7, 8, 9, 10, 12, 11 };

I want the output to be as follows:

SUM: value: 27, index of A: 4, index of B: 5
SUBTRACT: value: 14, index of A: 1, index of B: 5

I can do this by using a loop over two arrays

int SUM=-1000;
int IndexA = 0;
int IndexB = 0;
for (int i = 0; i < arrayA.Count(); i  )
    for (int j = 0; j < arrayB.Count(); j  )
    { 
        if(arrayA[i]  arrayB[j] > SUM)
        {
             SUM = arrayA[i]   arrayB[j];
             IndexA = i;
             IndexB = j;
        }
            
    }
Console.WriteLine("SUM: value: "   SUM.ToString()   ", index of A: "   
                 IndexA.ToString()   ", index of B: "   IndexB.ToString());


int SUBTRACT = -1000;
int _IndexA = 0;
int _IndexB = 0;
for (int i = 0; i < arrayA.Count(); i  )
   for (int j = 0; j < arrayB.Count(); j  )
   {
       if (arrayA[i] - arrayB[j] > SUBTRACT)
       {
            SUBTRACT = arrayA[i] - arrayB[j];
            _IndexA = i;
            _IndexB = j;
       }

       if ( arrayB[j] - arrayA[i] > SUBTRACT)
       {
             SUBTRACT = arrayB[j] - arrayA[i];
             _IndexA = i;
             _IndexB = j;
       }

   }
Console.WriteLine("SUBTRACT: value: "   SUBTRACT.ToString()   ", index of A: "   _IndexA.ToString()   ", index of B: "   _IndexB.ToString());

Is this the right solution? Is there a better way?

CodePudding user response：

If you sort the arrays with index, there is no need for loop over two arrays. You choose the largest of each array for SUM:

var ListA = arrayA.Select((x, i) => new { value = x, Index = i }).OrderBy(x=>x.value).ToList();
var ListB = arrayB.Select((x, i) => new { value = x, Index = i }).OrderBy(x=>x.value).ToList();

Console.WriteLine("SUM:{0}, index of A: {1}, index of B: {2}", ListA[ListA.Count - 1].value 
                 ListB[ListB.Count - 1].value, ListA[ListA.Count - 1].Index, ListB[ListB.Count - 1].Index);

SUM:27, index of A: 4, index of B: 5

To subtract, compare the largest item from arrayA with the smallest item from arrayB (or largest item from arrayB with the smallest item from arrayA):

if ((ListA[ListA.Count - 1].value - ListB[0].value) >= (ListB[ListB.Count - 1].value - ListA[0].value))
    Console.WriteLine("SUBTRACT: {0}, index of A: {1}, index of B: {2}", ListA[ListA.Count - 1].value - ListB[0].value, ListA[ListA.Count - 1].Index, ListB[0].Index);
else
    Console.WriteLine("SUBTRACT: {0}, index of A: {1}, index of B: {2}", ListB[ListB.Count - 1].value - ListA[0].value, ListA[0].Index, ListB[ListB.Count - 1].Index);

SUBTRACT: 14, index of A: 1, index of B: 5