Question

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

Answer 1

#include <stdio.h> 

void find_first_and_Last_position(int arr[], int len, int n, int *first, int *last) { 
    *first = -1, *last = -1; 
	
    for (int i = 0; i < len; i++) { 
        if (n != arr[i]) 
            continue; 
        if (*first == -1) 
            *first = i; 
        *last = i; 
    } 
} 

int main(void) 
{ 
	int arr[] = { 1, 3, 7, 8, 3, 1, 9 }; 
	int first, last;
    int n = 3; 
	
    find_first_and_Last_position(arr, sizeof(arr)/sizeof(int), n, &first, &last); 
	
	if (first != -1) 
        printf("First positions = %d Last positions = %d\n", first, last); 
    else
        printf("Not found\n"); 
	
    return 0; 
} 
  
  
  
/*
run:
  
First positions = 1 Last positions = 4
 
*/

 

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