I have a space separated list of int like below:

1 -2 3 1 -8 3 -2 5

I need an absolute sum of a specific range of that list i.e. from 4th index to 6th index. The result will be 10(from abs(-8-2)).

I can get the perfect result by using below code:

List<int> _subList = new List<int>();
string _input = Console.ReadLine();
List<int> _list = _input.Split(' ').Select(n => Convert.ToInt32(n)).ToList<int>();
var k =Math.Abs(_list.GetRange(3, 3).Where(x=>x<0).Sum());
Console.WriteLine(k);

But is there any way to do it without using Linq?

CodePudding user response：

But is there any way to do it without using Linq?

List<int> data = new List<int>() { 1, -2, 3, 1, -8, 3, -2, 5 };

long sum = 0;

var minIndex = 4;
var maxIndex = 6;

for (int i = minIndex; i <= maxIndex && i < data.Count; i  )
{
    if (data[i] < 0)
    {
        sum -= data[i];
    }
}

Above is using a for loop with the appropriate indices to get the values out, and using - rather than and Abs to get the output you expect.

If you explicitly need the string parsing:

string input = Console.ReadLine();

var data = input?.Split(",", StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries) ?? Array.Empty<string>();

long sum = 0;

var minIndex = 4;
var maxIndex = 6;

for (int i = minIndex; i <= maxIndex && i < data.Length; i  )
{
    if (int.TryParse(data[i], out var val) && val < 0)
    {
        sum -= val;
    }
}

Note you need to use ?. with the Split to handle Console.ReadLine returning null. And StringSplitOptions simplifies the trimming of whitespace.

CodePudding user response：

This is a great use case for LINQ extension methods.

1. split the string to get the constituent integer strings
2. skip to start offset
3. take desired element count (endOffset - startOffset 1)
4. convert string values to integers via projection
5. filter for negative values
6. project negation
7. aggregate the sum

.

string input = "...";
var startOffset = 4;
var endOffset = 6;

var absSum = input.Split(' ')
    .Skip(startOffset)
    .Take(endOffset - startOffset   1)
    .Select(s => Convert.ToInt32(s))
    .Where(i => 0 > i)
    .Select(i => -i)
    .Sum();

Without LINQ extension methods:

    var targetElements = input.Split(' ')
        //.Skip(startOffset).Task(endOffset - startOffset   1)
        .AsSpan(startOffset, endOffset - startOffset   1);
    
    var absSum = 0;
    
    foreach(var element in targetElements)
    {
        //.Select(s => Convert.ToInt32(s))
        var i = Convert.ToInt32(element);
        
        //.Where(i => 0 > i)
        if( 0 > i )
        {
            //.Sum()
            absSum  = i;
        }
    }
    
    // we know sum is negative so negate for absolute value
    absSum = -absSum;

CodePudding user response：

List<int> _subList = new List<int>();//1
            string _input = Console.ReadLine();//2
            List<int> _list = _input.Split(' ')//3
            .Select(n => Convert.ToInt32(n))//4
            .ToList<int>();//5
            var k =Math.Abs(_list.GetRange(3, 3)//6 
            .Where(x=>x<0).Sum());//7
            Console.WriteLine(k);

I think code below is right

• In //1 creates empty List
• In //2 read space as string
• In //3 getting numbers to int List
• In //4 Iterating and converting to numbers from string to int
• In //5 get All as List in type int
• In //6 I think Math.abs clear,GetRange(3,3) is same begin from range in math (3,3 3] thats 4,5,6
• In //7 Sum() for getting sum

CodePudding user response：

List<int> _subList = new List<int>();
string _input = Console.ReadLine();
List<int> _list = _input.Split(' ').Select(n => Convert.ToInt32(n)).ToList<int>();
var k =Math.Abs(_list.GetRange(3, 3).Where(x=>x<0).Sum());
Console.WriteLine(k);

Here _list.GetRange(3, 3) will create the sublist and then Where(x=>x<0).Sum() pick the negative values and sum it up and ulimately Math.Abs() will give the absolute value

But here i have used System.Linq; If anyone can provide with better solution other than manual looping would be appriciated