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  • spfa毒瘤算法

    终于知道怎么卡spfa(不优化)这一毒瘤算法了
    下面就是造数据代码,点数才1e5,边数379980
    随便测了一组数据:
    count: 831841219(入队次数)
    68917.096 ms(足够t到死了)

    //#pragma comment(linker, "/stack:200000000")
    //#pragma GCC optimize("Ofast,no-stack-protector")
    //#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
    //#pragma GCC optimize("unroll-loops")
    #include<bits/stdc++.h>
    #define fi first
    #define se second
    #define mp make_pair
    #define pb push_back
    #define pi acos(-1.0)
    #define ll long long
    #define vi vector<int>
    #define mod 1000000007
    #define ld long double
    #define C 0.5772156649
    #define ls l,m,rt<<1
    #define rs m+1,r,rt<<1|1
    #define pll pair<ll,ll>
    #define pil pair<int,ll>
    #define pli pair<ll,int>
    #define pii pair<int,int>
    #define cd complex<double>
    #define ull unsigned long long
    #define base 1000000000000000000
    #define Max(a,b) ((a)>(b)?(a):(b))
    #define Min(a,b) ((a)<(b)?(a):(b))
    #define fio ios::sync_with_stdio(false);cin.tie(0)
    template<typename T>
    inline T const& MAX(T const &a,T const &b){return a>b?a:b;}
    template<typename T>
    inline T const& MIN(T const &a,T const &b){return a<b?a:b;}
    inline void add(ll &a,ll b){a+=b;if(a>=mod)a-=mod;}
    inline void sub(ll &a,ll b){a-=b;if(a<0)a+=mod;}
    inline ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
    inline ll qp(ll a,ll b){ll ans=1;while(b){if(b&1)ans=ans*a%mod;a=a*a%mod,b>>=1;}return ans;}
    inline ll qp(ll a,ll b,ll c){ll ans=1;while(b){if(b&1)ans=ans*a%c;a=a*a%c,b>>=1;}return ans;}
    
    using namespace std;
    
    const double eps=1e-8;
    const ll INF=0x3f3f3f3f3f3f3f3f;
    const int N=100000+10,maxn=400000+10,inf=0x3f3f3f3f;
    
    struct edge{int a,b,c;};
    vector<edge>v;
    int main()
    {
        srand(time(0));
        freopen("a.txt","w",stdout);
        int n=10,m=10000;
        for(int i=1;i<=n;i++)
        {
            for(int j=1;j<=m;j++)
            {
                if(j!=m)
                {
                    v.pb({(i-1)*m+j,(i-1)*m+j+1,rand()%100000+1});
                    v.pb({(i-1)*m+j+1,(i-1)*m+j,rand()%100000+1});
                }
                if(i!=n)
                {
                    v.pb({(i-1)*m+j,i*m+j,1});
                    v.pb({i*m+j,(i-1)*m+j,1});
                }
            }
        }
        printf("%d %d
    ",n*m,v.size());
        random_shuffle(v.begin(),v.end());
        for(int i=0;i<v.size();i++)
            printf("%d %d %d
    ",v[i].a,v[i].b,v[i].c);
        return 0;
    }
    /********************
    
    ********************/
    

    spfa代码

    //#pragma comment(linker, "/stack:200000000")
    //#pragma GCC optimize("Ofast,no-stack-protector")
    //#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
    //#pragma GCC optimize("unroll-loops")
    #include<bits/stdc++.h>
    #define fi first
    #define se second
    #define mp make_pair
    #define pb push_back
    #define pi acos(-1.0)
    #define ll long long
    #define vi vector<int>
    #define mod 1000000007
    #define ld long double
    #define C 0.5772156649
    #define ls l,m,rt<<1
    #define rs m+1,r,rt<<1|1
    #define pll pair<ll,ll>
    #define pil pair<int,ll>
    #define pli pair<ll,int>
    #define pii pair<int,int>
    #define cd complex<double>
    #define ull unsigned long long
    #define base 1000000000000000000
    #define Max(a,b) ((a)>(b)?(a):(b))
    #define Min(a,b) ((a)<(b)?(a):(b))
    #define fio ios::sync_with_stdio(false);cin.tie(0)
    template<typename T>
    inline T const& MAX(T const &a,T const &b){return a>b?a:b;}
    template<typename T>
    inline T const& MIN(T const &a,T const &b){return a<b?a:b;}
    inline void add(ll &a,ll b){a+=b;if(a>=mod)a-=mod;}
    inline void sub(ll &a,ll b){a-=b;if(a<0)a+=mod;}
    inline ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
    inline ll qp(ll a,ll b){ll ans=1;while(b){if(b&1)ans=ans*a%mod;a=a*a%mod,b>>=1;}return ans;}
    inline ll qp(ll a,ll b,ll c){ll ans=1;while(b){if(b&1)ans=ans*a%c;a=a*a%c,b>>=1;}return ans;}
    
    using namespace std;
    
    const double eps=1e-8;
    const ll INF=0x3f3f3f3f3f3f3f3f;
    const int N=1000000+10,maxn=4000000+10,inf=0x3f3f3f3f;
    
    struct edge{
        int to,Next,c;
    }e[maxn];
    int cnt,head[N];
    void init()
    {
        cnt=0;
        memset(head,-1,sizeof head);
    }
    void add(int u,int v,int c)
    {
        e[cnt].to=v;
        e[cnt].c=c;
        e[cnt].Next=head[u];
        head[u]=cnt++;
    }
    bool vis[N];
    ll dis[N];
    void spfa()
    {
        memset(vis,0,sizeof vis);
        memset(dis,INF,sizeof dis);
        vis[1]=1;dis[1]=0;
        queue<int>q;
        q.push(1);
        int co=0;
        while(!q.empty())
        {
            int u=q.front();q.pop();
            vis[u]=0;
            for(int i=head[u];~i;i=e[i].Next)
            {
                int x=e[i].to;
                if(dis[x]>dis[u]+e[i].c)
                {
                    dis[x]=dis[u]+e[i].c;
                    if(!vis[x])
                    {
                        vis[x]=1;
                        q.push(x);
                        co++;
                    }
                }
            }
        }
        printf("count: %d
    ",co);
    }
    int main()
    {
        int a=clock();
        freopen("a.txt","r",stdin);
        init();
        int n,m;
        scanf("%d%d",&n,&m);
        for(int i=0;i<m;i++)
        {
            int a,b,c;
            scanf("%d%d%d",&a,&b,&c);
            add(a,b,c);
        }
        spfa();
        printf("%d
    ",dis[n]);
        int b=clock();
        printf("%.3f ms
    ",1.0*(b-a)/1000);
        return 0;
    }
    /********************
    
    ********************/
    
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  • 原文地址:https://www.cnblogs.com/acjiumeng/p/9432858.html
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