堆优化后的dijkstra算法模板（以hdu2544为例）

亦凉 2022-05-08 11:38 220阅读 0赞

## vector实现版，优点是代码量较少，缺点是常数较大。 ##

#pragma comment(linker, "/STACK:102400000,102400000")
    #include<unordered_map>
    #include<unordered_set>
    #include<algorithm>
    #include<iostream>
    #include<fstream>
    #include<complex>
    #include<cstdlib>
    #include<cstring>
    #include<cassert>
    #include<iomanip>
    #include<string>
    #include<cstdio>
    #include<bitset>
    #include<vector>
    #include<cctype>
    #include<cmath>
    #include<ctime>
    #include<stack>
    #include<queue>
    #include<deque>
    #include<list>
    #include<set>
    #include<map>
    using namespace std;
    #define pt(a) cout<<a<<endl
    #define debug test
    #define mst(ss,b) memset((ss),(b),sizeof(ss))
    #define rep(i,a,n) for (int i=a;i<=n;i++)
    #define per(i,a,n) for (int i=n-1;i>=a;i--)
    #define pii pair<int,int>
    #define fi first
    #define se second
    #define ll long long
    #define ull unsigned long long
    #define pb push_back
    #define mp make_pair
    #define inf 0x3f3f3f3f
    #define eps 1e-10
    #define PI acos(-1.0)
    const ll mod = 1e9+7;
    const int N = 1e3+10;
    
    ll qp(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
    int to[4][2]={
       {-1,0},{1,0},{0,-1},{0,1}};
    
    int n,m,d[N];
    struct eg{
        int to,len;
    };
    vector<eg> g[N];
    
    void dij() {
        mst(d,inf);
        d[1]=0;
        priority_queue<pii,vector<pii>,greater<pii> > pq;
        pq.push({0,1});
        while(!pq.empty()) {
            pii tp=pq.top(); pq.pop();
            int u=tp.se;
            if(d[u]!=tp.fi) continue;///等价于vis标记
            for(int i=0;i<g[u].size();i++) {
                eg v=g[u][i];
                if(d[u]+v.len<d[v.to]) {
                    d[v.to]=d[u]+v.len;
                    pq.push({d[v.to],v.to});
                }
            }
        }
        cout<<d[n]<<endl;
    }
    
    int main() {
        ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
        while(cin>>n>>m&&(n+m)) {
            for(int i=1;i<=n;i++) g[i].clear();
            for(int i=1;i<=m;i++) {
                int a,b,c;
                cin>>a>>b>>c;
                g[a].pb(eg{b,c});
                g[b].pb(eg{a,c});
            }
            dij();
        }
        return 0;
    }

# #

## 链式前向星实现边，优点是常数较小，缺点是代码量较大。 ##

#pragma comment(linker, "/STACK:102400000,102400000")
    #include<unordered_map>
    #include<unordered_set>
    #include<algorithm>
    #include<iostream>
    #include<fstream>
    #include<complex>
    #include<cstdlib>
    #include<cstring>
    #include<cassert>
    #include<iomanip>
    #include<string>
    #include<cstdio>
    #include<bitset>
    #include<vector>
    #include<cctype>
    #include<cmath>
    #include<ctime>
    #include<stack>
    #include<queue>
    #include<deque>
    #include<list>
    #include<set>
    #include<map>
    using namespace std;
    #define pt(a) cout<<a<<endl
    #define debug test
    #define mst(ss,b) memset((ss),(b),sizeof(ss))
    #define rep(i,a,n) for (int i=a;i<=n;i++)
    #define per(i,a,n) for (int i=n-1;i>=a;i--)
    #define pii pair<int,int>
    #define fi first
    #define se second
    #define ll long long
    #define ull unsigned long long
    #define pb push_back
    #define mp make_pair
    #define inf 0x3f3f3f3f
    #define eps 1e-10
    #define PI acos(-1.0)
    const ll mod = 1e9+7;
    const int N = 1e2+10;
    const int M = 1e4+10;
    
    ll qp(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
    ///int to[4][2]={
       {-1,0},{1,0},{0,-1},{0,1}};
    
    int n,m,d[N],hd[N],tot;
    int nt[M],to[M],w[M];
    
    void init() {
        tot=0;
        mst(hd,-1);
    }
    
    void add(int u,int v,int val) {
        to[tot]=v;
        w[tot]=val;
        nt[tot]=hd[u];
        hd[u]=tot++;
    }
    
    void dij() {
        mst(d,inf);
        d[1]=0;
        priority_queue<pii,vector<pii>,greater<pii> > pq;
        pq.push({0,1});
        while(!pq.empty()) {
            pii tp=pq.top();pq.pop();
            int u=tp.se;
            if(d[u]!=tp.fi) continue;
            for(int i=hd[u];~i;i=nt[i]) {
                int v=to[i];
                if(d[u]+w[i]<d[v]) {
                    d[v]=d[u]+w[i];
                    pq.push({d[v],v});
                }
            }
        }
        cout<<d[n]<<endl;
    }
    
    int main() {
        ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
        while(cin>>n>>m&&(n+m)) {
            init();
            for(int i=1;i<=m;i++) {
                int a,b,c;
                cin>>a>>b>>c;
                add(a,b,c);
                add(b,a,c);
            }
            dij();
        }
        return 0;
    }