Dijkstra算法 初探

今天看书新学的Dijkstra算法，可以用来计算带权值的无环有向图中单源最短距离。

下面是刚刚写的初版代码= =

// 20151118_Dijkstra.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <cstdio>#include <cstdlib>#include <cstring>#include <list>using namespace std;class point{public:int targetlist[100];int targetdistance[100];int targetlist_max;point(){targetlist_max = 0;}};point site[100];int site_max = 0;int loadmap(const char* filename){FILE* fp = fopen(filename, "r");if (fp == NULL){throw "NOOOOO";return -1;}int all;//点的总数fscanf(fp, "%d", &all);site_max = all;for (int i = 1;i <= all;i++){int target_all;//下行点总数量fscanf(fp, "%d", &target_all);site[i].targetlist_max = target_all;for (int j = 0;j < target_all;j++){int target_point, target_distance;//下行点和下行距离fscanf(fp, "%d %d", &target_point, &target_distance);site[i].targetdistance[j] = target_distance;site[i].targetlist[j] = target_point;}}fclose(fp);return 0;}bool known[100];bool have_distance[100];int dis[100];int lastpoint[100];list<int> todolist;void findmintrace(int startpoint){//初始化memset(known, false, sizeof(bool) * 100);memset(have_distance, false, sizeof(bool) * 100);memset(dis, 0, sizeof(int) * 100);memset(lastpoint, 0, sizeof(int) * 100);todolist.clear();//开始todolist.push_back(startpoint);for (int knowni = 0;knowni < site_max;knowni++){int currentpoint = todolist.front();//轮询到这个点，这个点就是已知的known[currentpoint] = true;todolist.pop_front();for (int j = 0;j < site[currentpoint].targetlist_max;j++){if (known[site[currentpoint].targetlist[j]]){//如果这个点是已知的continue;}else{if (have_distance[site[currentpoint].targetlist[j]]){//以前曾经计算过路程,现在只进行比较if (dis[site[currentpoint].targetlist[j]]>dis[currentpoint] + site[currentpoint].targetdistance[j]){//比较后发现原来的距离比较大，所以用新的替换掉dis[site[currentpoint].targetlist[j]] = dis[currentpoint] + site[currentpoint].targetdistance[j];//给这个点造成影响的是现在的这个点lastpoint[site[currentpoint].targetlist[j]] = currentpoint;}//如果路程更大的话就算了...}else{//以前没计算过路程//设置为计算过have_distance[site[currentpoint].targetlist[j]] = true;dis[site[currentpoint].targetlist[j]] = dis[currentpoint] + site[currentpoint].targetdistance[j];lastpoint[site[currentpoint].targetlist[j]] = currentpoint;}//无论如何这个点都是未知的，所以把这个点放到队列里面todolist.push_back(site[currentpoint].targetlist[j]);}}}}void showtrace(int endpoint){if (lastpoint[endpoint]!=0){showtrace(lastpoint[endpoint]);printf(" to ");}printf("BLOCK(%d) ", endpoint);}int main(){loadmap("map.txt");findmintrace(1);showtrace(7);    return 0;}

^_^ 一会儿稍微优化一下然后包装起来留着解决地图问题ww