呵呵

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <cstring>
typedef long long ll;
using namespace std;
const int N = 5 * 10000 + 5;

int xval[N], dep;
int n, a[N], pre[N];
ll d[N];
int pos[300], dd;

void work() {
	dep = dd = 0;
	for (int i = 1; i <= n; ++i) {
		scanf("%d", &a[i]);
		if (i > 1 && a[i] == a[i - 1]) {
			-- i;
			-- n;
			continue;
		}
		xval[dep++] = a[i];
	}

	sort(xval, xval + dep);
	dep = unique(xval, xval + dep) - xval;
	for (int i = 1; i <= n; ++i)
		a[i] = lower_bound(xval, xval + dep, a[i]) - xval;

	d[0] = 0;
	memset(pre, -1, sizeof pre);
	for (int i = 1; i <= n; ++i) {
		d[i] = i;
		bool done = false;
		for (int j = dd; j >= 1; --j)
			if (a[pos[j]] == a[i]) {
				for (int k = j; k >= 2; --k)
					pos[k] = pos[k - 1];
				pos[1] = i;
				done = true;
				break;
			}
		if (!done) {
			for (int j = dd + 1; j >= 2; --j)
				pos[j] = pos[j - 1];
			pos[1] = i;
			if (++dd > 250)
				dd = 250;
		}

		for (int j = 1; j <= dd && (j - 1) * (j - 1) <= i; ++j) {
			d[i] = min(d[i], d[pos[j]] + (j - 1) * (j - 1));
		}
		d[i] = min(d[i], (ll)dd * dd);
		pre[a[i]] = i;
	}

	printf("%I64d\n", d[n]);
}

int main() {
	while (~scanf("%d", &n))
		work();
	return 0;
}

HDU 5009 Paint Pearls _(:зゝ∠)_2014 ACM/ICPC Asia Regional Xi'an Online