給定邊和邊權
求出第一個點到所有點的最短距離
#include<bits/stdc++.h>
using namespace std;
int n,m,s,t;
const int inf=0x7fffffff;
int dis[10010];
vector<int> g[10010],e[10010];
struct Node{
int u,d;
Node(){}
Node(int _id,int _d){
u=_id,d=_d;
}//賦初值
friend bool operator<(Node a,Node b){
return a.d>b.d;
}//重載小於符號
};
priority_queue<Node> q;
void build(int u,int v,int w){
g[u].push_back(v);
e[u].push_back(w);
}
void dij(int s){//bfs
for(int i=1;i<=n;i++) dis[i]=inf;
dis[s]=0;
q.push(Node(s,0));
while(!q.empty()){
Node now=q.top();q.pop();
int u=now.u;
for(int i=0;i<g[u].size();i++){
int v=g[u][i];
int w=e[u][i];
if(dis[u]+w<dis[v]){
dis[v]=dis[u]+w;
q.push({v,dis[v]});
}
}
}
}
int main(){
//freopen("a.in","r",stdin);
//freopen("a.out","w",stdout);
while(cin>>n>>m>>s>>t){
memset(g,0,sizeof(g));
memset(e,0,sizeof(e));
for(int i=1;i<=m;i++){
int u,v,w;
cin>>u>>v>>w;
build(u,v,w);
build(v,u,w);
}
dij(s);
if(dis[t]==inf) cout<<"-1"<<endl;
else cout<<dis[t]<<endl;
}
return 0;
}
開學了QAQ,難過~
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