[模板]洛谷T3371 单源最短路径 SPFA+手工队列类

一年之后又重新学习此算法。。。233。。。

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
#include<ctime>
#include<cstdlib>

#include<string>
#include<stack>
//#include<queue>
#include<vector>
#include<algorithm>
#include<map>
#include<set>

using namespace std;

inline void read(int &x){
    x=0;
    char t=getchar();
    bool f=0;
    
    while(t<'0' || t>'9'){
        if(t=='-')f=1;
        t=getchar();
    }
    
    while(t>='0' && t<='9'){
        x=(x<<3)+(x<<1)+t-'0';
        t=getchar();
    }
    
    if(f)x=-x;
}

struct que{
    int head,tail;
    int q[10001];
    
    void build(){
        head=0;
        tail=0;
    }
    
    bool emp(){
        return head==tail;
    }
    
    void push(int x){
        q[tail]=x;
        tail++;
        if(tail==10001)tail=0;
    }
    
    void pop(){
        head++;
        if(head==10001)head=0;
    }
    
    int end(){
        if(tail==0)return q[10000];
        else return q[tail-1];
    }
    
    int begin(){
        return q[head];
    }
};

void start();
void SPFA();

que line;
bool pd[10010];
int d[10010];

int u[500010];
int v[500010];
int w[500010];
int first[10010];
int next[500010];

int n,m,s,i;

int main(){
    start();
    
    read(n);read(m);read(s);
    
    for(i=1;i<=m;i++){
        read(u[i]);read(v[i]);read(w[i]);
        next[i]=first[u[i]];
        first[u[i]]=i;
    }
    
    SPFA();
    
    for(i=1;i<=n;i++){
        if(d[i]!=0x3f3f3f3f)printf("%d ",d[i]);
        else printf("2147483647 ");
    }
    
    return 0;
}

void start(){
    line.build();
    memset(pd,0,sizeof(pd));
    memset(d,0x3f3f3f3f,sizeof(d));
    
    memset(first,0,sizeof(first));
    memset(next,0,sizeof(next));
}

void SPFA(){
    int t;
    
    line.push(s);
    pd[s]=1;
    d[s]=0;
    
    while(!line.emp()){
        t=first[line.begin()];
        while(t!=0){
            if(d[v[t]]>d[u[t]]+w[t]){
                d[v[t]]=d[u[t]]+w[t];
                if(pd[v[t]]==0){
                    line.push(v[t]);
                    pd[v[t]]=1;
                }
            }
            t=next[t];
        }
        pd[line.begin()]=0;
        line.pop();
    }
}