「NOI2019d2t1」弹跳
\(Description\):
一个 \(w \times h \ (1 \leq w, h \leq n)\) 的网格上有 \(n \ (1 \leq n \leq 7 \times 10 ^ 4)\) 个整点;
有 \(m \ (m \leq 1.5 \times 10 ^ 5)\) 次连边,每次连边长度为 \(t_i \ (1 \leq t_i \leq 10^4)\),以第 \(p_i\) 个整点为起点向坐标满足 \(l_i \leq x \leq r_i, \ d_i \leq y \leq u_i\) 的所有点连边。
求 \(1\) 号点为起点的单元最短路。
\(Sol\):
因为没有负权边,所以可以用到 \(dijkstra\) 的一个性质:以点 \(u\) 为起点松弛操作之后,到 \(u\) 的最短路就不会改变了。
可以用数据结构来维护矩阵上的点,最短路时不必把边建出来,只需每次找到一个最短路最小的矩阵,并以该矩阵中未被删除的点为起点进行松弛,并把这些点删除即可。
数据结构的选择很多,我写了线段树套 \(set\)。
时间复杂度 \(O(n\log_2^2n)\),空间复杂度 \(O(n \log_2 n)\)。
\(Source\):
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <set>
#include <vector>
#include <queue>
int in() {
int x = 0; char c = getchar(); bool f = 0;
while (c < '0' || c > '9')
f |= c == '-', c = getchar();
while (c >= '0' && c <= '9')
x = (x << 1) + (x << 3) + (c ^ 48), c = getchar();
return f ? -x : x;
}
template<typename T>inline void chk_min(T &_, T __) { _ = _ < __ ? _ : __; }
template<typename T>inline void chk_max(T &_, T __) { _ = _ > __ ? _ : __; }
const int N = 7e4 + 5;
struct city {
int x, y;
} a[N];
struct edge {
int p, t, l, r, d, u;
} b[N * 3];
int n, m, w, h;
int dis[N];
bool vis[N * 3];
std::vector<int> s[N];
typedef std::pair<int, int> pii;
std::priority_queue<pii> q;
std::queue<int> tmp;
struct segment_tree {
std::set<pii> t[N << 2];
void insert(int id_a, int tl = 1, int tr = w, int p = 1) {
t[p].insert(pii(a[id_a].y, id_a));
if (tl == tr)
return ;
int mid = (tl + tr) >> 1;
if (mid >= a[id_a].x)
insert(id_a, tl, mid, p << 1);
else
insert(id_a, mid + 1, tr, p << 1 | 1);
}
void remove(int id_a, int tl = 1, int tr = w, int p = 1) {
t[p].erase(pii(a[id_a].y, id_a));
if (tl == tr)
return ;
int mid = (tl + tr) >> 1;
if (mid >= a[id_a].x)
remove(id_a, tl, mid, p << 1);
else
remove(id_a, mid + 1, tr, p << 1 | 1);
}
void modify(int d, int id_b, int tl = 1, int tr = w, int p = 1) {
if (b[id_b].l <= tl && tr <= b[id_b].r) {
std::set<pii>::iterator x = std::lower_bound(t[p].begin(), t[p].end(), pii(b[id_b].d, 0));
for (; x != t[p].end() && x->first <= b[id_b].u; ++x) {
dis[x->second] = d;
for (unsigned i = 0; i < s[x->second].size(); ++i)
if (!vis[s[x->second][i]])
q.push(pii(-d - b[s[x->second][i]].t, s[x->second][i]));
tmp.push(x->second);
}
for (; !tmp.empty(); remove(tmp.front()), tmp.pop());
return ;
}
int mid = (tl + tr) >> 1;
if (mid >= b[id_b].l)
modify(d, id_b, tl, mid, p << 1);
if (mid < b[id_b].r)
modify(d, id_b, mid + 1, tr, p << 1 | 1);
}
} T;
int main() {
//freopen("in", "r", stdin);
n = in(), m = in(), w = in(), h = in();
for (int i = 1; i <= n; ++i)
a[i] = (city){in(), in()};
for (int i = 1; i <= m; ++i) {
b[i] = (edge){in(), in(), in(), in(), in(), in()};
s[b[i].p].push_back(i);
}
for (int i = 2; i <= n; ++i)
T.insert(i);
for (unsigned i = 0; i < s[1].size(); ++i)
q.push(pii(-b[s[1][i]].t, s[1][i]));
while (!q.empty()) {
int d = q.top().first, u = q.top().second;
q.pop();
if (vis[u])
continue;
vis[u] = 1;
T.modify(-d, u);
}
for (int i = 2; i <= n; ++i)
printf("%d\n", dis[i]);
return 0;
}