dijkstra （模板）

Posted 2021-01-10 sdfzsyq

突然意识到以前写的都是假的dij，感谢GhostCai神犇。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#define int long long

using namespace std;
const int MAXN = 10005;
const int MAXM = 500005;
const int inf = 2147483647;

inline int rd(){
    int x=0,f=1;char ch=getchar();
    while(!isdigit(ch)) {f=ch==‘-‘?0:1;ch=getchar();}
    while(isdigit(ch))  {x=(x<<1)+(x<<3)+ch-‘0‘;ch=getchar();}
    return f?x:-x;
}

int n,m,S,dis[MAXN],head[MAXN],cnt;
int to[MAXM],nxt[MAXM],val[MAXM];
bool vis[MAXN];

struct Node{
    int id,w;
    friend bool operator<(const Node A,const Node B){
        return A.w>B.w;
    }
};

inline void add(int bg,int ed,int w){
    to[++cnt]=ed,nxt[cnt]=head[bg],head[bg]=cnt,val[cnt]=w;
}

priority_queue<Node> Q;

void dijkstra(){
    for(int i=1;i<=n;i++) dis[i]=inf;
    Node now;now.id=S;now.w=0;dis[S]=0;
    int p,ww;Q.push(now);
    while(!Q.empty()){
        Node x=Q.top();Q.pop();p=x.id;ww=x.w;
        if(vis[p] || dis[p]!=ww) continue;
        vis[p]=1;int u;
        for(register int i=head[p];i;i=nxt[i]){
            u=to[i];
            if(dis[p]+val[i]<dis[u]) {
                dis[u]=dis[p]+val[i];
                now.id=u;now.w=dis[u];
                Q.push(now);
            }
        }
    }    
}

signed main(){
    n=rd(),m=rd(),S=rd();int x,y,z;
    for(int i=1;i<=m;i++){
        x=rd(),y=rd(),z=rd();
        add(x,y,z);
    }
    dijkstra();
    for(int i=1;i<=n;i++) printf("%lld ",dis[i]);
    return 0;
}

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