Question

How to find first and last positions of an element in a sorted array in C#

Answer 1

using System;
 
class Program
{
    static void find_first_and_Last_position(int[] arr, int n) { 
        int first = -1, last = -1; 
           
        for (int i = 0; i < arr.Length; i++) { 
            if (n != arr[i]) 
                continue; 
            if (first == -1) 
                first = i; 
            last = i; 
        } 
        if (first != -1) { 
            Console.WriteLine("First positions = " + first + " Last positions = " + last);
        } 
        else
            Console.Write("Not Found"); 
    } 
    static void Main() {
        int[] arr = {1, 3, 7, 8, 3, 1, 9}; 
        int n = 3; 
         
        find_first_and_Last_position(arr, n); 
    }
}
 
 
 
/*
run:
 
First positions = 1 Last positions = 4
 
*/

 

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Answer 2

using System;

class Program
{
    static Tuple<int, int> find_first_and_Last_position(int[] arr, int n) { 
        int first = -1, last = -1; 
          
        for (int i = 0; i < arr.Length; i++) { 
            if (n != arr[i]) 
                continue; 
            if (first == -1) 
                first = i; 
            last = i; 
        } 
        
        return Tuple.Create(first, last);
        
    } 
    static void Main() {
        int[] arr = {1, 3, 7, 8, 3, 1, 9}; 
        int n = 3; 
        
        var result = find_first_and_Last_position(arr, n); 
        
        if (result.Item1 != -1) { 
            Console.WriteLine("First positions = " + result.Item1 + " Last positions = " + result.Item2);
        } 
        else
            Console.Write("Not Found"); 
    }
}



/*
run:

First positions = 1 Last positions = 4

*/

 

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