【UOJ #244】【UER #7】短路

http://uoj.ac/contest/35/problem/244
对其他人来说好简单的一道题，我当时却不会做TWT
注定滚粗啊
题解很好的~

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
typedef long long ll;
const int N = 100003;
ll in() {
	ll k = 0, fh = 1; char c= getchar();
	for (; c < '0' || c > '9'; c = getchar())
		if (c == '-') fh = -1;
	for (; c >= '0' && c <= '9'; c = getchar())
		k = k * 10 + c - 48;
	return k * fh;
}

int n;
ll a[N], f[N], ans, now;

int main() {
	scanf("%d", &n);
	for (int i = 0; i <= n; ++i) a[i] = in();
	f[n] = a[n];
	now = a[n];
	ans = a[n] * (4 * n + 1);
	for (int i = n - 1; i >= 0; --i) {
		f[i] = f[i + 1] + now + a[i];
		if (a[i] < now) {
			now = a[i];
			ans = min(ans, f[i] * 2 + now * (4 * i - 1));
		}
	}
	printf("%lld
", ans);
	return 0;
}