Question

In C write a function called find_unique (). This function accepts a pointe integers, which consists of numbers that are greater than or equal to 0. The function searches the array for the unique integer. Not all arrays will have a unique integer, but if they do, then there will only be one unique number. A unique number is defined as the integer in the array that does not have at least one other matching value. If a unique number is located, then the value should be returned. Otherwise, -1 is returned.

Answer 1

#include <stdio.h>

//function takes 2 parameters, one a pointer to the array of integers

//second is the length of the array

int find_unique(int *arr, int len)

{

//first we will br finding out the maximum of the array

int max = *(arr);

for(int i = 1 ; i < len ; i++)

{

if(max < *(arr+i))

max = *(arr+i);

}

//creating an array

int counter[max+1];

//initialising its value to 0

for(int i = 0 ; i <= max ; i ++)

{

counter[i] = 0;

}

//every time we encounter any number n, then this loop will will increase the value of the counter array at index n,

//so if first if we get 2, then we will go to index 2 and add 1

//next if we get 3 then we will go to index 3 and add 1

//again if we gget 2, then we wil l goto index 2 and add 1, so not at index 2,we have value 2

for(int i = 0 ; i < len ; i ++)

{

counter[*(arr+i)]++;

}

//this way in the end, of at any index we encounter 1, then that means that index occured only once in the input array

for(int i = 0 ; i <= max ; i ++)

{

if(counter[i] == 1)

return i;

}

//if none foubnd then return -1

return -1;

}

int main(void) {

int arr[8] = {7, 6, 5, 5, 6, 7, 8, 7};

int len = sizeof(arr) / sizeof(arr[0]);

printf("\n\nUnique number is: %d\n", find_unique(arr, len));

return 0;

}

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