The Psychic Type

Alakazam has the unique ability to teleport itself during fights. He has realized that he can use this ability not just in Pokemon fights, but also during real-time manipulation of arrays. Abra, his non-evolution form has an interesting array of N integers, A1, A2, ..., AN-1, AN.

Since Alakazam wants to try his teleportation power on arrays too, he decides to formalize it: he can move from any position i to a position $A[i]$ in an array of the world. Now, he is currently standing at a position he calls S. He wants you to figure out if he can reach position E.

Example:

Input:  n = 5, a = [3,4,2,5,5], s = 1, e = 4
Output: Yes

Approach

C++

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

bool thePsychicType(int n, int arr[], int s, int e)
{
    int a[n + 1];
    for (int i = 1; i <= n; i++)
        a[i] = arr[i - 1];

    set<int> st;
    st.insert(s);
    int flag = 0;
    while (s != e)
    {
        s = a[s];
        if (st.find(s) != st.end())
        {
            flag = 1;
            break;
        }
        st.insert(s);
    }
    if (flag == 0)
        return true;
    else
        return false;
}
int main()
{

    int n = 5;

    int arr[] = {3, 4, 2, 5, 5};
    int s = 1, e = 4;

    if (thePsychicType(n, arr, s, e))
        cout << "Yes\n";
    else
        cout << "No\n";

    return 0;
}