diji模板

void diji(int x){
    fill(dis,dis+n,INT_MAX);
    dis[x] = ;
    for(int i=;i < n;i++) pre[i] = i;
    while(){
        int minn = INT_MAX;
        int v = -;
        for(int i=;i < n;i++){
            if(!vis[i]&&dis[i] < minn){
                v = i;
                minn = dis[i];
            }
        }
        if(v == -)break;
        vis[v] = ;
        for(int i=;i < n;i++){
            if(!vis[i]&&cost1[i][v]!=INT_MAX&&dis[v]+cost1[i][v]<dis[i]){
                dis[i] = dis[v] + cost1[i][v];
                pre[i] = v;
            }
        }
    }
}

初始化：

int main(){
    int m,s;
    cin >> n >> m >> s >> d;
    for(int i=;i < n;i++){
        for(int j=;j < n;j++){
            cost1[i][j] = INT_MAX;
            cost1[i][i] = ;
        }
    }
    for(int i=;i < m;i++){
        int x,y,a,b;
        cin >> x >> y >> a >> b;
        cost1[x][y] = a;
        cost1[y][x] = a;
        cost2[x][y] = b;
        cost2[y][x] = b;
    }
    diji(s);

    for(int i=;i < n;i++) cout << pre[i] << " ";
    return ;
}

diji+dfs模板

#include<iostream>
#include<vector>
using namespace std;
const int maxv = ;
const int INF = 1e9 + ;
int G[maxv][maxv], d[maxv], C[maxv][maxv];
int n, m, s, dd, mincost = INF;
bool vis[maxv];
vector<int>pre[maxv];
vector<int>temp, path;
void Dijkstra(int s)
{
    fill(d, d + maxv, INF);
    d[s] = ;
    while ()
    {
        int u = -, MIN = INF;
        for (int i = ; i < n; i++)
        {
            if (!vis[i]&&d[i] < MIN)MIN = d[i], u = i;
        }
        if (u == -)return;
        vis[u] = true;
        for (int i = ; i < n; i++)
        {
            if (!vis[i] && G[u][i])
            {
                if (d[u] + G[u][i] < d[i])
                {
                    d[i] = d[u] + G[u][i];
                    pre[i].clear();  //之前记录的不是最优的路，删去以后补上最优路的前项
                    pre[i].push_back(u);
                }
                else if (d[u] + G[u][i] == d[i])
                {
                    pre[i].push_back(u);//相等的话增加一个前项点
                }
            }
        }
    }
}
void DFS(int v)
{
    if (v == s)
    {
        temp.push_back(s);
        int tempcost = ;
        for (int i = temp.size() - ; i > ; i--)
        {
            int v = temp[i];
            int u = temp[i - ];
            tempcost += C[u][v];
        }
        if (tempcost < mincost)
        {
            mincost = tempcost;
            path = temp;
        }
        temp.pop_back();
        return;
    }
    temp.push_back(v);
    for (int i = ; i < pre[v].size(); i++)
        DFS(pre[v][i]);
    temp.pop_back();
}
int main()
{
    scanf("%d%d%d%d", &n, &m, &s, &dd);
    for (int i = ; i < m; i++)
    {
        int c1, c2, dis, cost;
        scanf("%d%d%d%d", &c1, &c2, &dis, &cost);
        G[c1][c2] = G[c2][c1] = dis;
        C[c1][c2] = C[c2][c1] = cost;
    }
    Dijkstra(s);
    DFS(dd);
    for (int i = path.size() - ; i >= ; i--)printf("%d ", path[i]);
    printf("%d %d", d[dd], mincost);
    return ;
}

——求相同路径的条数把pre[i]中有数的连城就好了8

https://www.liuchuo.net/archives/tag/dijkstra