CSU1321+SPFA

简单题

 /*
 简单的bfs
 */
 #include<algorithm>
 #include<iostream>
 #include<string.h>
 #include<stdlib.h>
 #include<stdio.h>
 #include<math.h>
 #include<queue>
 #include<stack>
 #include<map>
 #include<set>
 using namespace std;
 typedef long long int64;
 //typedef __int64 int64;
 typedef pair<int64,int64> PII;
 #define MP(a,b) make_pair((a),(b))
 const int inf = 0x3f3f3f3f;
 const double pi=acos(-1.0);
 const int dx[]={,-,,};
 const int dy[]={,,,-};
 const double eps = 1e-;
 const int maxm = ;
 const int maxn = ;
 struct Edge{
     int u,v,next,val;
 }edge[ maxm* ];
 int cnt ,head[ maxn ];
 bool vis[ maxn ];
 int dis1[ maxn ],dis2[ maxn ],girl[ maxn ];
 //int dp[ maxn ];
 queue<int>q;
 //int pre[ maxn ];
 void init(){
     cnt = ;
     memset( head,-,sizeof( head ) );
 }
 void addedge( int a,int b,int c ){
     edge[ cnt ].u = a;
     edge[ cnt ].v = b;
     edge[ cnt ].val = c;
     edge[ cnt ].next = head[ a ];
     head[ a ] = cnt ++;
 }

 int spfa( int n ){
     while( !q.empty() )
         q.pop();
     //memset( pre,-1,sizeof( pre ) );
     memset( vis,false,sizeof( vis ) );
     memset( dis1,0x3f,sizeof( dis1 ) );
     memset( dis2,0x3f,sizeof( dis2 ) );
     vis[  ] = true;
     q.push(  );
     dis1[  ] = ;
     dis2[  ] = girl[  ];
     //for( int i=head[1];i!=-1;i=edge[i].next ){
     //    pre[ edge[i].v ] = 1;
     //}
     while( !q.empty() ){
         int cur = q.front();
         q.pop();
         vis[ cur ] = false;
         for( int i=head[cur];i!=-;i=edge[i].next ){
             int nxt = edge[ i ].v;
             if( dis1[nxt]>dis1[cur]+edge[i].val ){
                 dis1[nxt] = dis1[cur]+edge[i].val;
                 //pre[ nxt ] = cur;
                 dis2[nxt] = dis2[cur]+girl[edge[i].v];
                 if( !vis[nxt] ){
                     vis[nxt] = true;
                     q.push( nxt );
                 }
             }
             else if( dis1[nxt]==dis1[cur]+edge[i].val ){
                 if( dis2[nxt]<dis2[cur]+girl[edge[i].v] ){
                     //pre[ nxt ] = cur;
                     dis2[nxt]=dis2[cur]+girl[edge[i].v];
                     if( !vis[nxt] ){
                         vis[nxt] = true;
                         q.push( nxt );
                     }
                 }
             }
         }
     }
     //printf("dis1[ %d ] = %d\n",n,dis1[n]);
     if( dis1[n]>=0x3f3f3f3f ) return -;
     else return dis2[ n ];
     /*
     int ans = 0;
     int cur = n;
     while( 1 ){
         ans += girl[ cur ];
         cur = pre[ cur ];
         if( cur==-1 ){
             break;
         }
     }
     return ans;
     */
 }

 int main(){
     int n;
     while( scanf("%d",&n)== ){
         int m;
         scanf("%d",&m);
         for( int i=;i<=n;i++ )
             scanf("%d",&girl[i]);
         int a,b,c;
         init();
         while( m-- ){
             scanf("%d%d%d",&a,&b,&c);
             //if( a==b ) continue;
             addedge( a,b,c );
             addedge( b,a,c );
         }
         printf("%d\n",spfa( n ) );
     }
     return ;
 }