#include <bits/stdc++.h>
using namespace std;
int f[2005][2][2005];
int a[2005];

int main() {
    freopen("color.in","r",stdin);
    freopen("color.out","w",stdout);
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
	int t;
	cin >> t;
	while (t--) {
		int n;
		cin >> n;
		for (int i = 1; i <= n; i++)
			cin >> a[i];
		memset(f, 0, sizeof(f));
		a[0]=-1;
		for (int i = 1; i <= n; i++) {
			for (int k = 1; k < i - 1; k++)
				f[i][0][k] = max(f[i][0][k], f[(i - 1)][0][k] + a[i] * (a[i - 1] == a[i]));
			for (int k = 1; k < i - 1; k++)
				f[i][0][i - 1] = max(f[i][0][i - 1], f[(i - 1)][1][k] + a[i] * (a[k] == a[i]));
			for (int k = 1; k < i - 1; k++)
				f[i][1][k] = max(f[i][1][k], f[(i - 1)][1][k] + a[i] * (a[i - 1] == a[i]));
			for (int k = 1; k < i - 1; k++)
				f[i][1][i - 1] = max(f[i][1][i - 1], f[(i - 1)][0][k] + a[i] * (a[k] == a[i]));
		}
		int ans = 0;
		for (int i = 1; i <= n; i++)
			ans = max(ans, max(f[n][1][i], f[n][0][i]));
		cout << ans << "\n";
	}
}

为什么这个代码在信友队的网站上测试会 RE 0分（csp s T3）