72 lines
1.1 KiB
C++
72 lines
1.1 KiB
C++
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/*
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Problem: Check if a given number is prime or not, using Recursion
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*/
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#include <bits/stdc++.h>
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using namespace std;
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// primeCheck is function that check whether the given number is prime or not and,
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// return true if prime else
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// return false
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bool primeCheck(int n, int i)
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{
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// Base cases
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if(n <= 2){
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// 2 is a prime
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if(n == 2){
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return true;
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}
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// 0 and 1 are not prime
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return false;
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}
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// if i divides n then n is not prime
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if(n % i == 0){
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return false;
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}
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if(i * i > n){
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return true;
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}
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// Check for next possible divisor
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return primeCheck(n, i + 1);
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}
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// Main
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int main()
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{
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cout << "Enter the number to check prime : " << endl;
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int n;
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cin >> n;
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//check and output
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if (primeCheck(n, 2))
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cout << "YES" <<endl;
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else
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cout << "NO" <<endl;
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return 0;
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}
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/*
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Time Complexity : O(sqrt(n))
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Input
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Enter the number to check prime : 5
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Output
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YES
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Input
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Enter the number to check prime : 10
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Output
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NO
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Input
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Enter the number to check prime : 33
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Output
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NO
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*/
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