https://codeforces.com/contest/1899/problem/C
题意：

给定一个数组a，Yarik希望找到一个非空子数组，使得这个子数组的元素交替具有奇偶性，并且和最大。我们需要帮助Yarik找到满足条件的子数组的最大和。

const int N = 2e5 + 10;
int n;
int dp[N][3];//ou ji

void solved()
{
    scanf("%d", &n);

    vector<int> a(n + 1);
    for(int i = 1; i <= n; i ++) scanf("%d", &a[i]);
    for(int i = 1; i <= n; i ++) dp[i][0] = -1e9, dp[i][1] = -1e9;

    int res = -1e9;
    for(int i = 1; i <= n; i ++)
    {
        //ji
        if(abs(a[i]) % 2)
            dp[i][1] = max(dp[i - 1][0] + a[i], a[i]);
        else
            dp[i][0] = max(dp[i - 1][1] + a[i], a[i]);

       // cout <<"i = " << i << " " << dp[i][0] << "  1=" << dp[i][1] << endl;

        res = max(res, max(dp[i][0], dp[i][1]));
    }
    printf("%d\n", res);
}

int main()
{
    int t; scanf("%d", &t);
    while(t --) solved();
    return 0;
}