C++ program to find sequence of indices of the team members

Suppose we have an array A with n elements and a number k. There are n students in a class. The rating of ith student is A[i]. We have to form a team with k students such that rating of all team members are distinct. If not possible return "Impossible", otherwise return the sequence of indices.

So, if the input is like A = [15, 13, 15, 15, 12]; k = 3, then the output will be [1, 2, 5].

Steps

To solve this, we will follow these steps −

Define two large arrays app and ans and fill them with
cnt := 0
n := size of A
   for initialize i := 1, when i <= n, update (increase i by 1), do:
      a := A[i - 1]
      if app[a] is zero, then:
         (increase app[a] by 1)
         increase cnt by 1;
         ans[cnt] := i
if cnt >= k, then:
   for initialize i := 1, when i <= k, update (increase i by 1), do:
      print ans[i]
Otherwise
   return "Impossible"

Example

Let us see the following implementation to get better understanding −

#include <bits/stdc++.h>
using namespace std;

void solve(vector<int> A, int k) {
   int app[101] = { 0 }, ans[101] = { 0 }, cnt = 0;
   int n = A.size();
   for (int i = 1; i <= n; i++) {
      int a = A[i - 1];
      if (!app[a]) {
         app[a]++;
         ans[++cnt] = i;
      }
   }
   if (cnt >= k) {
      for (int i = 1; i <= k; i++)
         cout << ans[i] << ", ";
   }
   else
      cout << "Impossible";
}
int main() {
   vector<int> A = { 15, 13, 15, 15, 12 };
   int k = 3;
   solve(A, k);
}