poj2387 最短路

题意：给出一堆双向路，求从N点到1点的最短路径，最裸的最短路径，建完边之后直接跑dij或者spfa就行

dij：

 1 #include<stdio.h>
 2 #include<string.h>
 3 #include<queue>
 4 #include<algorithm>
 5 #include<vector>
 6 using namespace std;
 7 typedef pair<int,int> pii;
 8 const int INF=0x3f3f3f3f;
 9
10 int head[1005],dist[1005],point[4005],val[4005],next[4005],size;
11
12 void add(int a,int b,int v){
13     int i;
14     for(i=head[a];~i;i=next[i]){
15         if(point[i]==b){
16             if(val[i]>v)val[i]=v;
17             return;
18         }
19     }
20     point[size]=b;
21     val[size]=v;
22     next[size]=head[a];
23     head[a]=size++;
24 }
25
26 struct cmp{
27     bool operator()(pii a,pii b){
28         return a.first>b.first;
29     }
30 };
31
32 void dij(int s){
33     int i;
34     priority_queue<pii,vector<pii>,cmp>q;
35     q.push(make_pair(0,s));
36     memset(dist,-1,sizeof(dist));
37     dist[s]=0;
38     while(!q.empty()){
39         pii p=q.top();
40         q.pop();
41         if(p.first>dist[p.second])continue;
42         for(i=head[p.second];~i;i=next[i]){
43             int j=point[i];
44             if(dist[j]==-1||dist[j]>p.first+val[i]){
45                 dist[j]=p.first+val[i];
46                 q.push(make_pair(dist[j],j));
47             }
48         }
49     }
50     printf("%d\n",dist[1]);
51 }
52
53 int main(){
54     int t,n;
55     while(scanf("%d%d",&t,&n)!=EOF){
56         int i,j;
57         size=0;
58         memset(head,-1,sizeof(head));
59         for(i=1;i<=t;i++){
60             int a,b,v;
61             scanf("%d%d%d",&a,&b,&v);
62             add(a,b,v);
63             add(b,a,v);
64         }
65         dij(n);
66     }
67     return 0;
68 }

dij

spfa：

 1 #include<stdio.h>
 2 #include<string.h>
 3 #include<queue>
 4 using namespace std;
 5
 6 int head[1005],dist[1005],next[4005],point[4005],val[4005],size;
 7 bool vis[1005];
 8
 9 void add(int a,int b,int v){
10     int i;
11     for(i=head[a];~i;i=next[i]){
12         if(point[i]==b){
13             if(val[i]>v)val[i]=v;
14             return;
15         }
16     }
17     point[size]=b;
18     val[size]=v;
19     next[size]=head[a];
20     head[a]=size++;
21 }
22
23 void spfa(int s,int p){
24     memset(vis,0,sizeof(vis));
25     memset(dist,-1,sizeof(dist));
26     queue<int>q;
27     vis[s]=1;
28     dist[s]=0;
29     q.push(s);
30     while(!q.empty()){
31         int i,t=q.front();
32         vis[t]=0;
33         q.pop();
34         for(i=head[t];~i;i=next[i]){
35             int j=point[i];
36             if(dist[j]==-1||dist[j]>dist[t]+val[i]){
37                 dist[j]=dist[t]+val[i];
38                 if(!vis[j]){
39                     q.push(j);
40                     vis[j]=1;
41                 }
42             }
43         }
44     }
45     printf("%d\n",dist[p]);
46 }
47
48 int main(){
49     int t,n;
50     while(scanf("%d%d",&t,&n)!=EOF){
51         int i,j;
52         memset(head,-1,sizeof(head));
53         size=0;
54         for(i=1;i<=t;i++){
55             int a,b,v;
56             scanf("%d%d%d",&a,&b,&v);
57             add(a,b,v);
58             add(b,a,v);
59         }
60         spfa(n,1);
61     }
62     return 0;
63 }

spfa