Dijkstra算法

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <map>
using namespace std;
/*==================================================*\
 | Dijkstra 数组实现O （N^2 ）
 | Dijkstra --- 数组实现( 在此基础上可直接改为STL 的Queue实现)
 | lowcost[] --- beg 到其他点的最近距离
 | path[] -- beg为根展开的树，记录父亲结点
 \*==================================================*/
#define INF 0x03F3F3F3F
//const int N;
map<int, int> path, vis;
void Dijkstra(map<int, map<int, int> > cost, map<int, int>& lowcost, int n, int beg) {
    int i, j, min;
//    memset(vis, 0, sizeof(vis));
    vis[beg] = 1;
    for (i = 0; i < n; i++) {
        lowcost[i] = cost[beg][i];
        path[i] = beg; //最大的距离
    }
    lowcost[beg] = 0; //起点到自身的距离肯定是0
    path[beg] = -1; //  树根的标记
    int pre = beg;
    for (i = 1; i < n; i++) {
        min = INF;
        for (j = 0; j < n; j++)
            // 下面的加法可能导致溢出,INF不能取太大
            //不能有负值，否则会出问题
            if (vis[j] == 0 && lowcost[pre] + cost[pre][j] < lowcost[j]) {
                lowcost[j] = lowcost[pre] + cost[pre][j];
                path[j] = pre;
            }
        for (j = 0; j < n; j++)
            if (vis[j] == 0 && lowcost[j] < min) { //选择下一个扩展的点
                min = lowcost[j];
                pre = j;
            }
        vis[pre] = 1;
    }
}
int main() {
    map<int, map<int, int> > cost;
    map<int, int> lowcost;
    for (int i = 0; i < 4; i++)
        for (int j = 0; j < 4; j++) {
            if (i != j)
                cost[i][j] = INF;
            else
                cost[i][j] = 0;
        }
    cost[0][1] = 3;
    cost[0][2] = 1;
    cost[0][3] = 10;
    cost[2][1] = 1;
    cost[2][3] = 1;

    for (int i = 0; i < 4; i++)
        vis[i]=0;
    Dijkstra(cost,lowcost, 4,0);
    for (int i = 0; i < 4; i++)
            cout<<lowcost[i]<<endl;
    return 0;
}