POJ 3259 wormholes

Topic Connection

http://poj.org/problem?id=3259

Wormholesdescription

While exploring he many farms, Farmer John has discovered a number of amazing wormholes. A wormhole is very peculiar because it's a one-way path that delivers the IT destination at a time that's before you entered the wormhole! Each of the FJ ' s farms comprises N (1≤ n ≤500) fields conveniently numbered 1.. N, m (1≤ m ≤2500) paths, and w (1≤ w ≤200) wormholes.

As FJ is a avid time-traveling fan, he wants to does the following:start at some field, travel through some paths and worm Holes, and return to the starting field a time before his initial departure. Perhaps he'll be able to meet himself:).

To help FJ find out whether this is possible or not, he'll supply you with complete maps to F (1≤ f ≤ 5) of his farms. No paths'll take longer than seconds to travel and no wormhole can bring FJ back in time by more than-seco Nds.

Input

Line 1: A single integer, F. F Farm descriptions follow.
Line 1 of each farm:three space-separated integers respectively: N, M, and W
Lines 2.. M+1 of each farm:three space-separated numbers (S, E, T) that describe, respectively: A bidirectional path between S and E that requires T seconds to traverse. The might is connected by more than one path.
Lines M+2.. M+W+1 of each farm:three space-separated numbers (S, E, T) that D Escribe, respectively:a One, path from S to E . Also moves the traveler back T sec Onds.

Output

Lines 1.. F: For each farm, output "YES" if FJ can achieve his goal, otherwise output "NO" (does not include the quotes).

Sample Input

2
3 3 1
1 2 2
1 3 4
2 3 1
3 1 3
3 2 1
1 2 3
2 3 4
3 1 8

Sample Output

NO
YES

SPFA judgment negative ring.

#include <algorithm> #include <iostream> #include <cstdlib> #include <cstring> #include < cstdio> #include <vector> #include <queue> #include <map>using std::map;using std::min;using std:: Find;using std::p air;using std::queue;using std::vector;using std::multimap; #define PB (E) push_back (e) #define SZ (c) ( int) (c). Size () #define MP (A, b) Make_pair (A, B) #define ALL (c) (c). Begin (), (c). End () #define ITER (c) __typeof ((c). Begin () ) #define CLS (arr, Val) memset (arr, Val, sizeof (arr)) #define Cpresent (C, E) (Find (All (c), (e))! = (c). End ()) #define REP (I, n) for (int i = 0; i < (int.) n; i++) #define TR (c, I) for (ITER (c) i = (c). Begin (); I! = (c). end (); ++i) const int n = 510;c onst int INF = 0x3f3f3f3f;struct SPFA {struct Edge {int to, w, next;}    G[n * 10];    BOOL Vis[n];    int tot, inq[n], head[n], dist[n];        inline void init (int n) {tot = 0;            Rep (i, n + 1) {Head[i] =-1;            Inq[i] = vis[i] = 0;        Dist[i] = INF; }   } inline void Add_edge (int u, int v, int w) {G[tot] = (edge) {V, W, Head[u]}; head[u] = tot++;        } inline void built (int m, int w) {int u, V, x;            while (m--) {scanf ("%d%d%d", &u, &v, &x);        Add_edge (U, V, x), Add_edge (V, u, x);            } while (w--) {scanf ("%d%d%d", &u, &v, &x);        Add_edge (U, V,-X);        }} inline bool Spfa (int n, int s = 1) {queue<int> q;        Q.push (s);        Dist[s] = 0, vis[s] = true;            while (!q.empty ()) {int u = q.front (); Q.pop ();            Vis[u] = false;                for (int i = head[u]; ~i; i = g[i].next) {Edge &e = G[i];                    if (dist[e.to] > Dist[u] + e.w) {dist[e.to] = Dist[u] + e.w;                        if (!vis[e.to]) {vis[e.to] = true;                        Q.push (e.to);                    inq[e.to]++;        }        } if (Inq[e.to] > N) return true;    }} return false;        } inline void Solve (int n, int m, int w) {init (n), built (M, W); Puts (SPFA (n)?    "YES": "NO");    }}go;int Main () {#ifdef LOCAL freopen ("In.txt", "R", stdin);    Freopen ("OUT.txt", "w+", stdout); #endif int T, N, M, W;    scanf ("%d", &t);        while (t--) {scanf ("%d%d%d", &n, &m, &w);    Go.solve (N, M, W); } return 0;}

Poj 3259 wormholes