백준 2156번 C++ 풀이

#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <queue>
using namespace std;
long wine[10001];
long didAteBefore[10001]; // i칸 , i-1칸 마심
long didAteBeforeBefore[10001]; //i칸, i-2칸 마심
long didAteBeforeBeforeBefore[10001]; //i칸, i-3칸 마심
int main() {
    cin.tie(NULL);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    for (int i = 0; i<n; i++){
        cin >> wine[i];
    }
    didAteBefore[0] = wine[0];
    didAteBeforeBefore[0] = wine[0];
    didAteBeforeBeforeBefore[0] = wine[0];
    if (n == 0){
        cout << wine[0];
        return 0;
    }else if (n==1){
        cout << wine[0]+ wine[1];
        return 0;
    }
    /**
     *  X O X
     *  X O O X
     *  X O O O X
     *
     */

    didAteBefore[1] = wine[0] + wine[1];
    didAteBeforeBefore[1] = wine[1];
    didAteBeforeBeforeBefore[1] = wine[1];

    didAteBefore[2] = wine[1] + wine[2];
    didAteBeforeBefore[2] = wine[0] + wine[2];
    didAteBeforeBeforeBefore[2] = wine[2];

    if (n==2 ){
        cout << max(didAteBefore[1], max(didAteBefore[2], didAteBeforeBefore[2]));
        return 0;
    }
    for (int i = 3; i<n; i++){
        didAteBefore[i] = max(didAteBeforeBefore[i-1], didAteBeforeBeforeBefore[i-1]) + wine[i];
        didAteBeforeBefore[i] = max(didAteBefore[i-2], max( didAteBeforeBefore[i-2], didAteBeforeBeforeBefore[i-2])) + wine[i];
        didAteBeforeBeforeBefore[i] = max(didAteBefore[i-3], max(didAteBeforeBefore[i-3], didAteBeforeBeforeBefore[i-3])) + wine[i];
    }
    long a = max (max(didAteBefore[n-1], didAteBeforeBefore[n-1]), didAteBeforeBeforeBefore[n-1]);
    long b = max (max(didAteBefore[n-2], didAteBeforeBefore[n-2]), didAteBeforeBeforeBefore[n-2]);

    cout << max(a,b);
    return 0;
}