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  • POJ 3259 Wormholes

    传送门

    AcWing 904 虫洞

    #include <iostream>
    #include <cstdio>
    #include <cstring>
    #include <queue>
    #include <stack>
    #include <algorithm>
    
    using namespace std;
    typedef long long ll;
    typedef pair<int, int> p;
    const int inf(0x3f3f3f3f);
    const int maxn(5e2 + 10);
    const int maxm(1e4 + 10);
    bool vis[maxn];
    int ecnt, head[maxn], cnt[maxn], dis[maxn];
    
    struct edge {
        int to, wt, nxt;
    } edges[maxm];
    
    template<typename T>
    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++;
    }
    
    bool spfa(int n)
    {
        vis[0] = true;
        dis[0] = 0;
        queue<int> q;
        q.push(0);
        while (not q.empty()) {
            int u = q.front();
            q.pop();
            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]) {
                        vis[v] = true;
                        q.push(v);
                        cnt[v] = cnt[u] + 1;
                        if (cnt[v] >= n + 1) {
                            return true;
                        }
                    }
                }
            }
        }
        return false;
    }
    
    int main()
    {
    #ifdef ONLINE_JUDGE
    #else
        freopen("input.txt", "r", stdin);
    #endif
        ios::sync_with_stdio(false);
        int t = read<int>();
        while (t--) {
            ecnt = 0;
            memset(head, -1, sizeof head);
            memset(vis, false, sizeof vis);
            memset(cnt, 0, sizeof cnt);
            memset(dis, 0x3f, sizeof dis);
            int n = read<int>(), m = read<int>(), w = read<int>();
            while (m--) {
                int u = read<int>(), v = read<int>(), w = read<int>();
                addEdge(u, v, w);
                addEdge(v, u, w);
            }
            while (w--) {
                int u = read<int>(), v = read<int>(), w = read<int>();
                addEdge(v, u, -w);
            }
            for (int i = 1; i <= n; ++i) {
                addEdge(0, i, 0);
            }
            printf("%s
    ", spfa(n) ? "YES" : "NO");
        }
        return 0;
    }
    
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  • 原文地址:https://www.cnblogs.com/singularity2u/p/13857423.html
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