HDU 2018 Cow Story DP

Basic DP

Problem URL:https://vjudge.net/problem/HDU-2018

Describe:

There is a cow that gives birth to a heifer every year.Every heifer starts in the fourth year and also has a heifer at the beginning of each year.Please program how many cows are in the nth year?

Input:

The input data consists of multiple test instances, one for each test instance, including an integer n (0 < n < 55), the meaning of n as described in the title.n=0 means the end of the input data, no processing.

Sample Input:

2
4
5
0

Samle Output

2
4
6

DP[1] = 1
DP[2] = 2
DP[3] = 3
DP[4] = 4
DP[i] = DP[i-1] + DP[i-3]  i>=5

AC code :

#include <iostream>
#include <algorithm>
#include <bits/stdc++.h>
using namespace std;
int DP[55];
int main()
{
    int  n;
    while(cin>>n && n!=0)
    {
        DP[1] = 1;
        DP[2] = 2;
        DP[3] = 3;
        DP[4] = 4;
        for(int j = 5;j < 55;j++)
            DP[j] = DP[j-1] + DP[j-3];
        cout<<DP[n]<<endl;
    }
    return 0;
}