# C Program to Find Missing Numbers in an Array of Size N-1 with Numbers[1,N]

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This is a C Program to identify the missing number in an integer array of size n-1 with numbers[1,N].

Problem Description

This C Program Identifies the Missing Number in an Integer Array of Size N-1 with Numbers[1,N].

Problem Solution

Take input from the user and performs bitwise operations as shown in the program below.

Program/Source Code

Here is source code of the C Program to To Identify the Missing Number in an Integer Array of Size N-1 with Numbers[1,N]. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

```/*
* C Program To Identify the Missing Number in an Integer
* Array of Size N-1 with Numbers[1,N]
*/
#include <stdio.h>
#define MAX 15
int missing_number_array(int [],int);

int main()
{
int a[MAX], num, i, n;

printf("enter the range of array\n");
scanf("%d", &n);
for (i = 0;i < n;i++)
{
printf("enter a[%d]element into the array:", i);
scanf("%d", &a[i]);
}
num = missing_number_array(a, n);
printf("The missing number -> %d\n", num);
}

/* To find the missing number in array */
int missing_number_array(int a[],  int n)
{
int i;
int s1 = 0;
int s2 = 0;

for (i = 0;i < n;i++)
s1 = s1 ^ a[i];
for (i = 1;i <= n + 1;i++)
s2 = s2 ^ i;
return (s1 ^ s2);
}```
Program Explanation

In this C Program, we are reading the range of array using ‘n’ variable. Using for loop we are entering the coefficient element values of an array. The missing_number_array() function is used to find the missing number in array.

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Then ‘s1’ and ‘s2’ variables are used to compute the Binary XOR operation, copies the bit if it is set in one operand but not both. Again compute the Binary XOR Operation is performed for s1 and s2 variable value and returns the value. Print the missing number in an integer array of size N-1 with numbers [1, N].

Runtime Test Cases
```
\$ cc bit29.c
\$ a.out
enter the range of array
9
enter a[0]element into the array:1
enter a[1]element into the array:5
enter a[2]element into the array:2
enter a[3]element into the array:7
enter a[4]element into the array:3
enter a[5]element into the array:4
enter a[6]element into the array:10
enter a[7]element into the array:9
enter a[8]element into the array:6
The missing number -> 8
\$ a.out
enter the range of array
4
enter a[0]element into the array:1
enter a[1]element into the array:5
enter a[2]element into the array:3
enter a[3]element into the array:2
The missing number -> 4
\$ a.out
enter the range of array
4
enter a[0]element into the array:3
enter a[1]element into the array:2
enter a[2]element into the array:5
enter a[3]element into the array:4
The missing number -> 1```

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