2019 ICPC Asia Yinchuan Regional H. Delivery Route

传送门

Version 1 Tarjan + Dijkstra

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using p = pair<int, int>;
const double pi(acos(-1));
const int inf(0x3f3f3f3f);
const int mod(1e9 + 7);
const int maxn(1e5 + 10);
const int maxm(1e6 + 10);
int ecnt, head[maxn];
int tim, scnt, dfn[maxn], low[maxn], id[maxn];
int dis[maxn];
bool vis[maxn];
stack<int> st;
vector<int> scc[maxn];
priority_queue<p, vector<p>, greater<p>> q;

struct edge {
    int to, wt, nxt;
} edges[maxm];

template<typename T = int>
inline const T read()
{
    T x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        x = (x << 3) + (x << 1) + ch - '0';
        ch = getchar();
    }
    return x * f;
}

template<typename T>
inline void write(T x, bool ln)
{
    if (x < 0) {
        putchar('-');
        x = -x;
    }
    if (x > 9) write(x / 10, false);
    putchar(x % 10 + '0');
    if (ln) putchar(10);
}

void addEdge(int u, int v, int w)
{
    edges[ecnt].to = v;
    edges[ecnt].wt = w;
    edges[ecnt].nxt = head[u];
    head[u] = ecnt++;
}

void tarjan(int u)
{
    dfn[u] = low[u] = ++tim;
    st.push(u);
    vis[u] = true;
    for (int i = head[u]; compl i; i = edges[i].nxt) {
        int v = edges[i].to;
        if (not dfn[v]) {
            tarjan(v);
            low[u] = min(low[u], low[v]);
        } else if (vis[v]) {
            low[u] = min(low[u], dfn[v]);
        }
    }
    if (dfn[u] == low[u]) {
        ++scnt;
        int v = -1;
        do {
            v = st.top();
            st.pop();
            vis[v] = false;
            id[v] = scnt;
            scc[scnt].push_back(v);
        } while (u not_eq v);
    }
}

void dijkstra(int s)
{
    for (int u : scc[s]) {
        q.push(p(dis[u], u));
    }
    while (not q.empty()) {
        int u = q.top().second;
        q.pop();
        if (vis[u]) continue;
        vis[u] = true;
        for (int i = head[u]; compl i; i = edges[i].nxt) {
            int v = edges[i].to, w = edges[i].wt;
            if (id[u] == id[v] and dis[v] > dis[u] + w) {
                dis[v] = dis[u] + w;
                q.push(p(dis[v], v));
            }
        }
    }
}

int main()
{
#ifdef ONLINE_JUDGE
#else
    freopen("input.txt", "r", stdin);
#endif
    memset(head, -1, sizeof head);
    memset(dis, 0x3f, sizeof dis);
    int n = read(), x = read(), y = read(), s = read();
    while (x--) {
        int u = read(), v = read(), w = read();
        addEdge(u, v, w);
        addEdge(v, u, w);
    }
    while (y--) {
        int u = read(), v = read(), w = read();
        addEdge(u, v, w);
    }
    tarjan(s);
    dis[s] = 0;
    for (int i = scnt; i; --i) {
        dijkstra(i);
        for (int u : scc[i]) {
            for (int j = head[u]; compl j; j = edges[j].nxt) {
                int v = edges[j].to, w = edges[j].wt;
                if (id[u] not_eq id[v]) {
                    dis[v] = min(dis[v], dis[u] + w);
                }
            }
        }
    }
    for (int i = 1; i <= n; ++i) {
        if (dis[i] == inf) {
            puts("NO PATH");
        } else {
            write(dis[i], true);
        }
    }
    return 0;
}

Version 2 SPFA Swap-SLF 优化

SPFA 玄学优化 https://www.luogu.com.cn/blog/xhhkwy/spfa-hacker-orzorz

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using p = pair<int, int>;
const double pi(acos(-1));
const int inf(0x3f3f3f3f);
const int mod(1e9 + 7);
const int maxn(1e5 + 10);
const int maxm(1e6 + 10);
int ecnt, head[maxn];
int dis[maxn];
bool vis[maxn];
deque<int> q;

struct edge {
    int to, wt, nxt;
} edges[maxm];

template<typename T = int>
inline const T read()
{
    T x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') {
        if (ch == '-') f = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9') {
        x = (x << 3) + (x << 1) + ch - '0';
        ch = getchar();
    }
    return x * f;
}

template<typename T>
inline void write(T x, bool ln)
{
    if (x < 0) {
        putchar('-');
        x = -x;
    }
    if (x > 9) write(x / 10, false);
    putchar(x % 10 + '0');
    if (ln) putchar(10);
}

void addEdge(int u, int v, int w)
{
    edges[ecnt].to = v;
    edges[ecnt].wt = w;
    edges[ecnt].nxt = head[u];
    head[u] = ecnt++;
}

void swap_slf()
{
    if (q.size() > 2 and dis[q.front()] > dis[q.back()]) {
        swap(q.front(), q.back());
    }
}

void spfa(int src)
{
    dis[src] = 0;
    q.push_back(src);
    vis[src] = true;
    while (not q.empty()) {
        int u = q.front();
        q.pop_front();
        swap_slf();
        vis[u] = false;
        for (int i = head[u]; compl i; i = edges[i].nxt) {
            int v = edges[i].to, w = edges[i].wt;
            if (dis[v] > dis[u] + w) {
                dis[v] = dis[u] + w;
                if (not vis[v]) {
                    q.push_back(v);
                    swap_slf();
                    vis[v] = true;
                }
            }
        }
    }
}

int main()
{
#ifdef ONLINE_JUDGE
#else
    freopen("input.txt", "r", stdin);
#endif
    memset(head, -1, sizeof head);
    memset(dis, 0x3f, sizeof dis);
    int n = read(), x = read(), y = read(), s = read();
    while (x--) {
        int u = read(), v = read(), w = read();
        addEdge(u, v, w);
        addEdge(v, u, w);
    }
    while (y--) {
        int u = read(), v = read(), w = read();
        addEdge(u, v, w);
    }
    spfa(s);
    for (int i = 1; i <= n; ++i) {
        if (dis[i] == inf) {
            puts("NO PATH");
        } else {
            write(dis[i], true);
        }
    }
    return 0;
}