Uva-10986_sending Email (forward star +dijkstra)

Test instructions: Give you point, edge, the shortest distance from the beginning to the end.
The problem: Because the data volume of the topic is particularly large, so need to use adjacency table to save the edge, then the Dijkstra algorithm a little magic change can be, it would be time-out, do a heap optimization preparation, the result card time is over, can say very happy.
Note that SPFA will time out.

#include <queue> #include <cmath> #include <stack> #include <cstdio> #include <cstring># Include <cstdlib> #include <iostream> #include <algorithm>using namespace std;const int maxn = 20050; const int INF = 1e9 + 7;struct node{int next,to,w;}    S[50050*2];int head[maxn],f[maxn],dis[maxn],num,n,m,s,t;void Add (int u,int v,int w) {s[num].to = v;    S[num].next = Head[u];    S[NUM].W = W; Head[u] = num++;}    void Spfa () {int i,j,min,k,u;        for (i=0;i<n;i++) {dis[i] = INF;    F[i] = 0;        } for (i=head[s];i!=-1;i=s[i].next) {u = s[i].to;    Dis[u] = S[I].W;    } F[s] = 1;        for (i=0;i<n;i++) {MIN = INF;        K =-1;                for (j=0;j<n;j++) {if (!f[j]&&dis[j]<min) {MIN = Dis[j];            K = J;        }} if (Min==inf) break;        F[k] = 1;           for (J=head[k];j!=-1;j=s[j].next) { u = s[j].to;        if (!f[u]&&dis[k]+s[j].w<dis[u]) dis[u] = dis[k] + s[j].w;    }} if (Dis[t]!=inf) printf ("%d\n", dis[t]); else printf ("unreachable\n");}    int main () {int t,i,a,b,c,k = 1;    scanf ("%d", &t);        while (t--) {scanf ("%d%d%d%d", &n,&m,&s,&t);        for (i=0;i<n;i++) head[i] =-1;        num = 0;            for (i=0;i<m;i++) {scanf ("%d%d%d", &a,&b,&c);            Add (A,B,C);        Add (B,A,C);        } printf ("Case #%d:", k++);    SPFA (); } return 0;}

Uva-10986_sending Email (forward star +dijkstra)