图算法模版

Dijkstra算法：

#include<iostream>
#include<queue>
#include<stack>
#include<functional>
#define N 1000
#define MAX 1000000
using namespace std;

int arcs[N][N];    //邻接矩阵

//Dijkstra算法（稠密）
bool visit[N];    //集合 S , visit[i] = true, i 属于集合 S
int d[N];    //存放最短路径距离
int parent[N];    //parent[i],路径存在时，存放节点 i 的前驱节点；不存在时，-1

void Dijkstra(int s, int n)
{
    for (int i = 0; i < n; ++i){    //初始化
        visit[i] = 0; 
        d[i] = arcs[s][i];
        if (d[i] < MAX) parent[i] = s;
        else
            parent[i] = -1;
    }

    d[s] = 0; visit[s] = true;
    for (int i = 0; i < n - 1; ++i){    //循环 n-1 次
        int min = MAX;
        int v=0;
        for (int j = 0; j < n; ++j){    //在集合V-S中，选到 S 距离最小的点 v
            if (!visit[j] && d[j] < min){
                v = j; min = d[j];
            }
        }
        visit[v] = true;    //所选点 v 加入集合 S 中
        for (int j = 0; j < n; ++j){
            if (!visit[j] && (min + arcs[v][j] < d[j])){
                d[j] = min + arcs[v][j];
                parent[j] = v;
            }
        }
    }

}
//Dijkstra算法路径打印
void printPath(int s, int w)
{
    vector<int> v;
    if (parent[w] == -1){
        printf("path is not exit
");
        return;
    }
    do{
        v.push_back(w);
    } while (w = parent[w], w != s);
    v.push_back(s);
    int len = v.size();
    for (int i = len - 1; i > 0; --i)
        printf("%d ", v[i]);
    printf("%d
", v[0]);
}

int main()
{
    int n;
    cin >> n;
    for (int i = 0; i < n; ++i)
        for (int j = 0; j < n; ++j)
            cin >> arcs[i][j];
    Dijkstra(0, n);

    for (int i = 0; i < n-1; ++i)
        cout << d[i] << ' ';
    cout << d[n - 1] << endl;
    for (int i = 0; i < n - 1; ++i)
        cout << parent[i] << ' ';
    cout << parent[n - 1] << endl;
    for (int i = 0; i < n; ++i)
        printPath(0, i);
}

/*
输入样例：
6
1000000  7  9  1000000  1000000  14
7  1000000  11000000 15 1000000  1000000
9  11000000 1000000  11 1000000  2
1000000  15 11 1000000  6  1000000
1000000  1000000  1000000  6  1000000  9
14 1000000  2  1000000  9  1000000

6
1000000 1000000 10 100000 30 100
1000000 1000000 5 1000000 1000000 1000000
1000000 1000000 1000000 50 1000000 1000000
1000000 1000000 1000000 1000000 1000000 10
1000000 1000000 1000000 20 1000000 60
1000000 1000000 1000000 1000000 1000000 1000000
*/