CSU1321+SPFA

/*
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[]={1,-1,0,0};
const int dy[]={0,0,1,-1};
const double eps = 1e-8;
const int maxm = 1000005;
const int maxn = 1005;
struct Edge{
int u,v,next,val;
}edge[ maxm*2 ];
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 = 0;
memset( head,-1,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[ 1 ] = true;
q.push( 1 );
dis1[ 1 ] = 0;
dis2[ 1 ] = girl[ 1 ];
//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!=-1;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
);
if( dis1
>=0x3f3f3f3f ) return -1;
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)==1 ){
int m;
scanf("%d",&m);
for( int i=1;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 0;
}