M. Lucky Numbers – Codeforces Problem Solution in C++

Disclaimer: Make sure you tried enough before checking the solution

Problem: https://codeforces.com/group/MWSDmqGsZm/contest/219432/problem/M

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int luckyNumbers[100000]={0},flag=0;
	luckyNumbers[4] = 1;
	luckyNumbers[7] = 1;
	luckyNumbers[44] = 1;
	luckyNumbers[47] = 1;
	luckyNumbers[74] = 1;
	luckyNumbers[77] = 1;
	luckyNumbers[444] = 1;
	luckyNumbers[447] = 1;
	luckyNumbers[474] = 1;
	luckyNumbers[477] = 1;
	luckyNumbers[774] = 1;
	luckyNumbers[777] = 1;
	luckyNumbers[747] = 1;
	luckyNumbers[744] = 1;
	luckyNumbers[4747] = 1;
	luckyNumbers[4444] = 1;
	luckyNumbers[4447] = 1;
	luckyNumbers[4474] = 1;
	luckyNumbers[4477] = 1;
	luckyNumbers[4777] = 1;
	luckyNumbers[4744] = 1;
	luckyNumbers[4774] = 1;
	luckyNumbers[7474] = 1;
	luckyNumbers[7777] = 1;
	luckyNumbers[7774] = 1;
	luckyNumbers[7747] = 1;
	luckyNumbers[7744] = 1;
	luckyNumbers[4477] = 1;
	luckyNumbers[7444] = 1;
	luckyNumbers[7477] = 1;
	luckyNumbers[7447] = 1;
	int num1,num2;
	cin>>num1>>num2;
	for(int i=num1;i<=num2;i++){ // 4 5 6 7 8 9 ..... 20
		if(luckyNumbers[i] == 1){
			cout<<i<<" ";
			flag=1;
		}
	}
	if(flag == 0){
		cout<<"-1"<<endl;
	}

	
}

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