« First Index of Number in the array.

Problem

First Index of Number in array

Given an array of length N and an integer x, you need to find and return the first index of integer x present in the array. Return -1 if it is not present in the array. First index means, the index of first occurrence of x in the input array. Do this recursively. Indexing in the array starts from 0.

Input Format :

Line 1 : An Integer N i.e. size of array

Line 2 : N integers which are elements of the array, separated by spaces

Line 3 : Integer x

Output Format :

first index or -1

Constraints :

1 <= N <= 10^3

Sample Input :

4 9 8 10 8 8

Sample Output :

1

Solution

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1#include <iostream>
2#include <iomanip>
3#include <algorithm>
4#include <string>
5#include <cstring>
6#include <vector>
7#include <cmath>
8#include <map>
9#include <climits>
10// climits for INT_MIN
11#include <unordered_map>
12using namespace std;
13
14int firstIndex(int input[], int size, int x)
15{
16    if (input[0] == x)
17    {
18        return 0;
19    }
20
21    if (size == 1)
22    {
23        return -1;
24    }
25    else
26    {
27        int an = firstIndex(input + 1, size - 1, x);
28        if (an >= 0)
29        {
30            return an + 1;
31        }
32        else
33        {
34            return an;
35        }
36    }
37}
38int main()
39{
40    int n;
41    cin >> n;
42
43    int *input = new int[n];
44
45    for (int i = 0; i < n; i++)
46    {
47        cin >> input[i];
48    }
49
50    int x;
51
52    cin >> x;
53
54    cout << firstIndex(input, n, x) << endl;
55
56    return 0;
57}