• 「NOI2019d2t1」弹跳


    题目链接

    \(Description\)

    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;
    \(m \ (m \leq 1.5 \times 10 ^ 5)\) 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。

    \(1\) 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;
    }
    
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  • 原文地址:https://www.cnblogs.com/15owzLy1/p/11520848.html
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