DP UVALive 6506 Padovan Sequence

/*
题意：两行数字，相邻列一上一下，或者隔一列两行都可以，从左到右选择数字使和最大
DP：状态转移方程：dp[i][j] = max (dp[i][j], dp[1-i][j-1] + a[i][j], dp[i/1-i][j-2] + a[i][j]);
要从前面一个转态推过来啊，我比赛写反了，内功不够:(
*/
#include <cstdio>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <ctime>
#include <cstdlib>
using namespace std;

const int MAXN = 1e5 + 10;
const int INF = 0x3f3f3f3f;
int a[2][MAXN];
int dp[2][MAXN];

int main(void)        //UVALive 6506 Padovan Sequence
{
//    freopen ("K.in", "r", stdin);

int t;    scanf ("%d", &t);
while (t--)
{
int n;    scanf ("%d", &n);
memset (dp, 0, sizeof (dp));

for (int i=0; i<=1; ++i)
{
for (int j=1; j<=n; ++j)
{
scanf ("%d", &a[i][j]);
}
}

dp[0][1] = a[0][1];    dp[1][1] = a[1][1];
int ans = max (dp[0][1], dp[1][1]);
for (int j=2; j<=n; ++j)
{
for (int i=0; i<=1; ++i)
{
dp[i][j] = max (dp[i][j], dp[1-i][j-1] + a[i][j]);
if (j > 2)
{
dp[i][j] = max (dp[i][j], dp[i][j-2] + a[i][j]);
dp[i][j] = max (dp[i][j], dp[1-i][j-2] + a[i][j]);
}
ans = max (ans, dp[i][j]);
}
}

printf ("%d\n", ans);
}

return 0;
}