C++ Program to find out the distinct elements in a given sequence

Suppose we are given three integer numbers n, x, y, and z. We have to make a sequence from the given integers where the first item of the sequence is (x modulo 2³¹). Other than the first element, other elements in the sequence a_i = (a_(i-1) * y + z) modulo 2³¹ , where 1 ≤ i ≤ n - 1. We have to find out the number of distinct integers in the sequence we made.

So, if the input is like n = 5, x = 1, y = 2, z = 1, then the output will be 5.

The unique values are {1, 3, 7, 15, 31}. So, the answer is 5.

To solve this, we will follow these steps −

• MOD := 2^31
• Define an array temp
• resize the array temp to the value of MOD
• p := x mod MOD
• temp[p] := true
• ans := 1
• for initialize i := 1, when i
• p := ((p * y) + z) mod MOD
• if temp[p] is true, then −
  • Come out from the loop
• increase ans by 1
• temp[p] := true

Example

Let us see the following implementation to get better understanding −

#include 
#include 
#include 
#include 
#include 
using namespace std;

const long long MOD = 2147483648;

int solve(int n, long long x, long long y, long long z) {
   vector temp;
   temp.resize(MOD);
   long long p = x % MOD;
      temp[p] = true;
      int ans = 1;
      for (int i = 1; i 

Input
5, 1, 2, 1
Output
5