[백준 2193] 이친수 (DP) (C/C++)

#include <iostream>
#include <algorithm>
using namespace std;
 
int N;
long long dp[100][2];
 
long long solve(int cnt, int num)
{
    if(cnt == 1)
    {
        return num == 0 ? 0 : 1;
    }
    
    if(dp[cnt][num] != 0)
    {
        return dp[cnt][num];
    }
    
    if(num == 1)
    {
        dp[cnt][num] = solve(cnt-1, 0);
    }
    else
    {
        dp[cnt][num] = solve(cnt-1, 0) + solve(cnt-1, 1);
    }
    
    return dp[cnt][num];
}
 
int main(void)
{
//    freopen("B2193_input.txt", "r", stdin);
    
    cin >> N;
    
    cout << solve(N, 0) + solve(N, 1); 
    
    return 0;
}