« All indices of a number in array.

Problem

All Indices of Number in array

Given an array of length N and an integer x, you need to find all the indexes where x is present in the input array. Save all the indexes in an array (in increasing order). 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 :

indexes where x is present in the array (separated by space)

Constraints :

1 <= N <= 10^3

Sample Input :

5 9 8 10 8 8 8

Sample Output :

1 3 4

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 allIndexes(int input[], int size, int x, int output[])
15{
16    if (size == 0)
17    {
18        return 0;
19    }
20    int m = allIndexes(input, size - 1, x, output);
21    if (input[size - 1] == x)
22    {
23        output[m] = size - 1;
24        return m + 1;
25    }
26    else
27    {
28        return m;
29    }
30}
31
32int main()
33{
34    int n;
35    cin >> n;
36
37    int *input = new int[n];
38
39    for (int i = 0; i < n; i++)
40    {
41        cin >> input[i];
42    }
43
44    int x;
45
46    cin >> x;
47
48    int *output = new int[n];
49
50    int size = allIndexes(input, n, x, output);
51    for (int i = 0; i < size; i++)
52    {
53        cout << output[i] << " ";
54    }
55    cout << endl;
56
57    delete[] input;
58
59    delete[] output;
60    return 0;
61}