_bzoj1003 [ZJOI2006]物流运输【预处理】

传送门：http://www.lydsy.com/JudgeOnline/problem.php?id=1003

预处理出第i天到第j天走一条航线时的最短路。

#include <cstdio>
#include <cstring>
#include <algorithm>

const int maxn = 105, maxm = 25, maxe = 1005;

int n, m, K, e, t1, t2, t3, dd;
int head[maxm], to[maxe << 1], next[maxe << 1], w[maxe << 1], lb;
int p[10005], a[10005], b[10005];
char book[maxm], inq[maxm];
int que[maxm], head_, tail, h, d[maxm], price[maxn][maxn];
int f[maxn];

inline void ist(int aa, int ss, int ww) {
	to[lb] = ss;
	next[lb] = head[aa];
	head[aa] = lb;
	w[lb] = ww;
	++lb;
}
inline void spfa(int start, int end) {
	memset(book, 0, sizeof book);
	for (int i = 0; i < dd; ++i) {
		if (a[i] <= end && b[i] >= start) {
			book[p[i]] = 1;
		}
	}
	if (book[1] || book[m]) {
		price[start][end] = 0x3c3c3c3c;
		return;
	}
	memset(que, 0, sizeof que);
	memset(d, 0x3c, sizeof d);
	memset(inq, 0, sizeof inq);
	head_ = tail = 0;
	que[tail++] = 1;
	inq[1] = true;
	d[1] = 0;
	while (head_ != tail) {
		h = que[head_++];
		inq[h] = 0;
		if (head_ == m) {
			head_ = 0;
		}
		for (int j = head[h]; j != -1; j = next[j]) {
			if (!book[to[j]] && d[to[j]] > d[h] + w[j]) {
				d[to[j]] = d[h] + w[j];
				if (!inq[to[j]]) {
					inq[to[j]] = 1;
					que[tail++] = to[j];
					if (tail == m) {
						tail = 0;
					}
				}
			}
		}
	}
	price[start][end] = d[m];
}

int main(void) {
	//freopen("in.txt", "r", stdin);
	memset(next, -1, sizeof next);
	memset(head, -1, sizeof head);
	scanf("%d%d%d%d", &n, &m, &K, &e);
	while (e--) {
		scanf("%d%d%d", &t1, &t2, &t3);
		ist(t1, t2, t3);
		ist(t2, t1, t3);
	}
	scanf("%d", &dd);
	for (int i = 0; i < dd; ++i) {
		scanf("%d%d%d", p + i, a + i, b + i);
	}
	
	for (int i = 1; i <= n; ++i) {
		for (int j = i; j <= n; ++j) {
			spfa(i, j);
		}
	}
	f[0] = -K;
	for (int i = 1; i <= n; ++i) {
		f[i] = 2147483647;
		for (int j = 0; j < i; ++j) {
			if (price[j + 1][i] < 0x3c3c3c3c) {
				f[i] = std::min(f[i], f[j] + price[j + 1][i] * (i - j));
			}
		}
		f[i] += K;
	}
	printf("%d
", f[n]);
	return 0;
}