板子，单源最短路+堆优化

Posted 2021-02-28 sweetlittlebaby

#include<iostream>
#include<cstdio>
#include<queue>
#include<cstring>
#include<algorithm>
typedef long long LL;
using namespace std;
LL RD(){
    LL out = 0,flag = 1;char c = getchar();
    while(c < ‘0‘ || c >‘9‘){if(c == ‘-‘)flag = -1;c = getchar();}
    while(c >= ‘0‘ && c <= ‘9‘){out = out * 10 + c - ‘0‘;c = getchar();}
    return flag * out;
    }
const LL maxn = 1000019,INF = 0xfffffffffffffff;
LL head[maxn],nume = 1;
struct Node{
    LL v,dis,nxt;
    }E[maxn << 3];
void add(LL u,LL v,LL dis){
    E[++nume].nxt = head[u];
    E[nume].v = v;
    E[nume].dis = dis;
    head[u] = nume;
    }
LL num, nr, s;
bool vis[maxn];
LL d[maxn];
struct node{
    LL u, d;
    bool operator < (const node &a)const{
        return d > a.d;
        }
    };
void Djs(LL s){
    for(LL i = 1;i <= num;i++)d[i] = INF;
    priority_queue<node>Q;
    d[s] = 0;
    Q.push((node){s, d[s]});
    while(!Q.empty()){
        LL u = Q.top().u;Q.pop();
        if(vis[u])continue;
        vis[u] = 1;
        for(LL i = head[u];i;i = E[i].nxt){
            LL v = E[i].v, dis = E[i].dis;
            if(d[u] + dis < d[v]){
                d[v] = d[u] + dis;
                Q.push((node){v, d[v]});
                }
            }
        }
    }
int main(){
    num = RD();nr = RD();s = RD();
    for(int i = 1;i <= nr;i++){
        LL u = RD(), v = RD(), dis = RD();
        add(u, v, dis);
        }
    Djs(s);
    for(int i = 1;i <= num;i++)printf("%lld ", d[i]);
    return 0;
}

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 struct SYM{
 4     int to,next,w;
 5 }edge[500010];
 6 struct LKJ{
 7     int v,c;
 8     bool operator <(const LKJ &a)const {
 9         return c>a.c;
10     }
11 };
12 priority_queue<LKJ,vector<LKJ> > q;
13 int head[101000],vis[101000],tot,dis[101000],n,m,k;
14 void add(int x,int y,int w){
15     edge[++tot].to=y;
16     edge[tot].w=w;
17     edge[tot].next=head[x];
18     head[x]=tot;
19 }
20 void dij(int s){
21      dis[s]=0;
22      LKJ hh;hh.v=s;hh.c=0; 
23      q.push(hh);
24      while(!q.empty()){
25          LKJ tmp=q.top();q.pop();
26          int x=tmp.v;
27         if(vis[x]) continue;vis[x]=1;
28          for(int i=head[x];i;i=edge[i].next)
29              if(!vis[edge[i].to]&&dis[edge[i].to]>dis[x]+edge[i].w){
30                  dis[edge[i].to]=dis[x]+edge[i].w;
31                  hh.v=edge[i].to;hh.c=dis[edge[i].to];
32                  q.push(hh);
33              }
34     }
35 }
36 int main(){
37     memset(dis,127,sizeof(dis));
38     int x,y,w;
39     scanf("%d%d%d",&n,&m,&k);
40     for(int i=1;i<=m;i++){
41         scanf("%d%d%d",&x,&y,&w);
42         add(x,y,w);
43     }
44     dij(k);
45     for(int i=1;i<=n;i++){
46         if(dis[i]==2139062143) printf("2147483647 ");
47         else printf("%d ",dis[i]);
48     }
49     return 0;
50 }